The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Virgil Percec - One of the best experts on this subject based on the ideXlab platform.
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self assembly of dendritic Dipeptides as a model of chiral selection in primitive biological systems
Topics in Current Chemistry, 2012Co-Authors: Brad M. Rosen, Cecile Roche, Virgil PercecAbstract:Biological macromolecules are homochiral, composed of sequences of stereocenters possessing the same repeated absolute configuration. This chapter addresses the mechanism of homochiral selection in polypeptides. In particular, the relationship between the stereochemistry (l or d) of structurally distinct α-amino acids is explored. Through functionalization of Tyr–Xaa Dipeptides with self-assembling dendrons, the effect of stereochemical sequence of the dipeptide on the thermodynamics of self-assembly and the resulting structural features can be quantified. The dendritic dipeptide approach effectively isolates the stereochemical information of the shortest sequence of stereochemical information possible in polypeptide, while simultaneously allowing for dendron driven tertiary and quaternary structure formation and subsequent transfer of chiral information from the dipeptide to the dendritic sheath. This approach elucidates a mechanism of selecting a homochiral relationship between dissimilar but neighboring α-amino acids through thermodynamic preference for homochirality in solution-phase and bulk supramolecular helical polymerization.
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Programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide.
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV-vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermodynamics and mechanism of self-assembly. It was found that the highest degree of stereochemical purity, enantiopure homochiral dendritic Dipeptides, exhibits the most thermodynamically favorable self-assembly process in solution corresponding to the greatest degree of helical order and intracolumnar crystallization in solid state. Reducing the stereochemical purity of the dendritic dipeptide through heterochirality or by partially or fully racemizing the dendritic dipeptide destructively interferes with the self-assembly process. All dendritic Dipeptides were shown to coassemble into single columns regardless of their stereochemistry. Because these columns exhibit no deracemization, the thermodynamic advantage of enantiopurity and homochirality suggests a mechanism for stereochemical selection and chiral amplification.
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programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV−vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermody...
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principles of self assembly of helical pores from dendritic Dipeptides
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, Mihai Peterca, Sami Nummelin, Monika J. Sienkowska, Paul A. HeineyAbstract:The self-assembly of the dendritic Dipeptides (4-3,4-3,5)nG2-CH2-Boc-l-Tyr-l-Ala-OMe and their achiral dendritic alcohol (4-3,4-3,5)nG2-CH2OH precursors, both with n = 1–16, where n represents the number of methylenic units in the alkyl groups of the dendron, are reported. All chiral dendritic Dipeptides and achiral dendritic alcohols self-assemble into helical porous columns that are stable in both solution and solid state. The pore diameter (Dpore) of the columns self-assembled from dendritic Dipeptides is ≈10 A larger than that of structures assembled from dendritic alcohols. The increase of the Dpore at the transition from dendritic alcohol to dendritic dipeptide is accompanied by a decreased solid angle of the building block. This trend is in agreement with previous pore size-solid angle dependences observed with different protective groups of the dipeptide and primary structures of the dendron. However, within the series of dendritic alcohols and dendritic Dipeptides with various n, the Dpore increases when the solid angle increases. The results of these investigations together with those of previous studies on the role of dipeptide stereochemistry and protective groups on this self-assembly process provide the molecular principles required to program the construction of supramolecular helical pores with diameter controlled at the A level from a single dendritic dipeptide architecture. These principles are expected to be valid for libraries of dendritic Dipeptides based on dendrons and Dipeptides with various primary structures.
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Principles of self-assembly of helical pores from dendritic Dipeptides
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, Mihai Peterca, Sami Nummelin, Monika J. Sienkowska, Paul A. HeineyAbstract:The self-assembly of the dendritic Dipeptides (4-3,4-3,5)nG2-CH2-Boc-L-Tyr-L-Ala-OMe and their achiral dendritic alcohol (4-3,4-3,5)nG2-CH2OH precursors, both with n = 1-16, where n represents the number of methylenic units in the alkyl groups of the dendron, are reported. All chiral dendritic Dipeptides and achiral dendritic alcohols self-assemble into helical porous columns that are stable in both solution and solid state. The pore diameter (D(pore)) of the columns self-assembled from dendritic Dipeptides is approximately 10 A larger than that of structures assembled from dendritic alcohols. The increase of the D(pore) at the transition from dendritic alcohol to dendritic dipeptide is accompanied by a decreased solid angle of the building block. This trend is in agreement with previous pore size-solid angle dependences observed with different protective groups of the dipeptide and primary structures of the dendron. However, within the series of dendritic alcohols and dendritic Dipeptides with various n, the D(pore) increases when the solid angle increases. The results of these investigations together with those of previous studies on the role of dipeptide stereochemistry and protective groups on this self-assembly process provide the molecular principles required to program the construction of supramolecular helical pores with diameter controlled at the A level from a single dendritic dipeptide architecture. These principles are expected to be valid for libraries of dendritic Dipeptides based on dendrons and Dipeptides with various primary structures.
Brad M. Rosen - One of the best experts on this subject based on the ideXlab platform.
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self assembly of dendritic Dipeptides as a model of chiral selection in primitive biological systems
Topics in Current Chemistry, 2012Co-Authors: Brad M. Rosen, Cecile Roche, Virgil PercecAbstract:Biological macromolecules are homochiral, composed of sequences of stereocenters possessing the same repeated absolute configuration. This chapter addresses the mechanism of homochiral selection in polypeptides. In particular, the relationship between the stereochemistry (l or d) of structurally distinct α-amino acids is explored. Through functionalization of Tyr–Xaa Dipeptides with self-assembling dendrons, the effect of stereochemical sequence of the dipeptide on the thermodynamics of self-assembly and the resulting structural features can be quantified. The dendritic dipeptide approach effectively isolates the stereochemical information of the shortest sequence of stereochemical information possible in polypeptide, while simultaneously allowing for dendron driven tertiary and quaternary structure formation and subsequent transfer of chiral information from the dipeptide to the dendritic sheath. This approach elucidates a mechanism of selecting a homochiral relationship between dissimilar but neighboring α-amino acids through thermodynamic preference for homochirality in solution-phase and bulk supramolecular helical polymerization.
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Programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide.
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV-vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermodynamics and mechanism of self-assembly. It was found that the highest degree of stereochemical purity, enantiopure homochiral dendritic Dipeptides, exhibits the most thermodynamically favorable self-assembly process in solution corresponding to the greatest degree of helical order and intracolumnar crystallization in solid state. Reducing the stereochemical purity of the dendritic dipeptide through heterochirality or by partially or fully racemizing the dendritic dipeptide destructively interferes with the self-assembly process. All dendritic Dipeptides were shown to coassemble into single columns regardless of their stereochemistry. Because these columns exhibit no deracemization, the thermodynamic advantage of enantiopurity and homochirality suggests a mechanism for stereochemical selection and chiral amplification.
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programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV−vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermody...
Andres E Dulcey - One of the best experts on this subject based on the ideXlab platform.
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Programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide.
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV-vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermodynamics and mechanism of self-assembly. It was found that the highest degree of stereochemical purity, enantiopure homochiral dendritic Dipeptides, exhibits the most thermodynamically favorable self-assembly process in solution corresponding to the greatest degree of helical order and intracolumnar crystallization in solid state. Reducing the stereochemical purity of the dendritic dipeptide through heterochirality or by partially or fully racemizing the dendritic dipeptide destructively interferes with the self-assembly process. All dendritic Dipeptides were shown to coassemble into single columns regardless of their stereochemistry. Because these columns exhibit no deracemization, the thermodynamic advantage of enantiopurity and homochirality suggests a mechanism for stereochemical selection and chiral amplification.
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programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV−vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermody...
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principles of self assembly of helical pores from dendritic Dipeptides
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, Mihai Peterca, Sami Nummelin, Monika J. Sienkowska, Paul A. HeineyAbstract:The self-assembly of the dendritic Dipeptides (4-3,4-3,5)nG2-CH2-Boc-l-Tyr-l-Ala-OMe and their achiral dendritic alcohol (4-3,4-3,5)nG2-CH2OH precursors, both with n = 1–16, where n represents the number of methylenic units in the alkyl groups of the dendron, are reported. All chiral dendritic Dipeptides and achiral dendritic alcohols self-assemble into helical porous columns that are stable in both solution and solid state. The pore diameter (Dpore) of the columns self-assembled from dendritic Dipeptides is ≈10 A larger than that of structures assembled from dendritic alcohols. The increase of the Dpore at the transition from dendritic alcohol to dendritic dipeptide is accompanied by a decreased solid angle of the building block. This trend is in agreement with previous pore size-solid angle dependences observed with different protective groups of the dipeptide and primary structures of the dendron. However, within the series of dendritic alcohols and dendritic Dipeptides with various n, the Dpore increases when the solid angle increases. The results of these investigations together with those of previous studies on the role of dipeptide stereochemistry and protective groups on this self-assembly process provide the molecular principles required to program the construction of supramolecular helical pores with diameter controlled at the A level from a single dendritic dipeptide architecture. These principles are expected to be valid for libraries of dendritic Dipeptides based on dendrons and Dipeptides with various primary structures.
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Principles of self-assembly of helical pores from dendritic Dipeptides
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, Mihai Peterca, Sami Nummelin, Monika J. Sienkowska, Paul A. HeineyAbstract:The self-assembly of the dendritic Dipeptides (4-3,4-3,5)nG2-CH2-Boc-L-Tyr-L-Ala-OMe and their achiral dendritic alcohol (4-3,4-3,5)nG2-CH2OH precursors, both with n = 1-16, where n represents the number of methylenic units in the alkyl groups of the dendron, are reported. All chiral dendritic Dipeptides and achiral dendritic alcohols self-assemble into helical porous columns that are stable in both solution and solid state. The pore diameter (D(pore)) of the columns self-assembled from dendritic Dipeptides is approximately 10 A larger than that of structures assembled from dendritic alcohols. The increase of the D(pore) at the transition from dendritic alcohol to dendritic dipeptide is accompanied by a decreased solid angle of the building block. This trend is in agreement with previous pore size-solid angle dependences observed with different protective groups of the dipeptide and primary structures of the dendron. However, within the series of dendritic alcohols and dendritic Dipeptides with various n, the D(pore) increases when the solid angle increases. The results of these investigations together with those of previous studies on the role of dipeptide stereochemistry and protective groups on this self-assembly process provide the molecular principles required to program the construction of supramolecular helical pores with diameter controlled at the A level from a single dendritic dipeptide architecture. These principles are expected to be valid for libraries of dendritic Dipeptides based on dendrons and Dipeptides with various primary structures.
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programming the internal structure and stability of helical pores self assembled from dendritic Dipeptides via the protective groups of the peptide
Journal of the American Chemical Society, 2005Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, And Monika J Sienkowska, Mihai Peterca, Paul A. HeineyAbstract:The synthesis of dendritic Dipeptides (4-3,4-3,5)12G2−CH2−X−l-Tyr−l-Ala−OMe with X = Boc, Moc, and Ac; their self-assembly in bulk and in solution; and the structural and retrostructural analysis of their supramolecular helical porous assemblies are reported. The dimensions, structure, internal order, thermal stability of the supramolecular helical pores, and conformations of the dendron and supramolecular dendrimer are programmed by the nature of the protective groups of the dipeptide. The ability of the protective groups to program the structure of the helical pore reveals the simplest design strategy that complements the more complex strategies based on the architecture of the dendron, the stereochemistry, and the structure of the dipeptide.
Mihai Peterca - One of the best experts on this subject based on the ideXlab platform.
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Programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide.
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV-vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermodynamics and mechanism of self-assembly. It was found that the highest degree of stereochemical purity, enantiopure homochiral dendritic Dipeptides, exhibits the most thermodynamically favorable self-assembly process in solution corresponding to the greatest degree of helical order and intracolumnar crystallization in solid state. Reducing the stereochemical purity of the dendritic dipeptide through heterochirality or by partially or fully racemizing the dendritic dipeptide destructively interferes with the self-assembly process. All dendritic Dipeptides were shown to coassemble into single columns regardless of their stereochemistry. Because these columns exhibit no deracemization, the thermodynamic advantage of enantiopurity and homochirality suggests a mechanism for stereochemical selection and chiral amplification.
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programming the supramolecular helical polymerization of dendritic Dipeptides via the stereochemical information of the dipeptide
Journal of the American Chemical Society, 2011Co-Authors: Brad M. Rosen, Andres E Dulcey, Mihai Peterca, Kentaro Morimitsu, Pawaret Leowanawat, Ana-maria Resmerita, Mohammad R. Imam, Virgil PercecAbstract:Many natural biomacromolecules are homochiral and are built from constituents possessing identical handedness. The construction of synthetic molecules, macromolecules, and supramolecular structures with tailored stereochemical sequences can detail the relationship between chirality and function and provide insight into the process that leads to the selection of handedness and amplification of chirality. Dendritic Dipeptides, previously reported from our laboratory, self-assemble into helical porous columns and serve as fundamental mimics of natural porous helix-forming proteins and supramolecular polymers. Herein, the synthesis of all stereochemical permutations of a self-assembling dendritic dipeptide including homochiral, heterochiral, and differentially racemized variants is reported. A combination of CD/UV−vis spectroscopy in solution and in film, X-ray diffraction, and differential scanning calorimetry studies in solid state established the role of the stereochemistry of the dipeptide on the thermody...
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principles of self assembly of helical pores from dendritic Dipeptides
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, Mihai Peterca, Sami Nummelin, Monika J. Sienkowska, Paul A. HeineyAbstract:The self-assembly of the dendritic Dipeptides (4-3,4-3,5)nG2-CH2-Boc-l-Tyr-l-Ala-OMe and their achiral dendritic alcohol (4-3,4-3,5)nG2-CH2OH precursors, both with n = 1–16, where n represents the number of methylenic units in the alkyl groups of the dendron, are reported. All chiral dendritic Dipeptides and achiral dendritic alcohols self-assemble into helical porous columns that are stable in both solution and solid state. The pore diameter (Dpore) of the columns self-assembled from dendritic Dipeptides is ≈10 A larger than that of structures assembled from dendritic alcohols. The increase of the Dpore at the transition from dendritic alcohol to dendritic dipeptide is accompanied by a decreased solid angle of the building block. This trend is in agreement with previous pore size-solid angle dependences observed with different protective groups of the dipeptide and primary structures of the dendron. However, within the series of dendritic alcohols and dendritic Dipeptides with various n, the Dpore increases when the solid angle increases. The results of these investigations together with those of previous studies on the role of dipeptide stereochemistry and protective groups on this self-assembly process provide the molecular principles required to program the construction of supramolecular helical pores with diameter controlled at the A level from a single dendritic dipeptide architecture. These principles are expected to be valid for libraries of dendritic Dipeptides based on dendrons and Dipeptides with various primary structures.
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Principles of self-assembly of helical pores from dendritic Dipeptides
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, Mihai Peterca, Sami Nummelin, Monika J. Sienkowska, Paul A. HeineyAbstract:The self-assembly of the dendritic Dipeptides (4-3,4-3,5)nG2-CH2-Boc-L-Tyr-L-Ala-OMe and their achiral dendritic alcohol (4-3,4-3,5)nG2-CH2OH precursors, both with n = 1-16, where n represents the number of methylenic units in the alkyl groups of the dendron, are reported. All chiral dendritic Dipeptides and achiral dendritic alcohols self-assemble into helical porous columns that are stable in both solution and solid state. The pore diameter (D(pore)) of the columns self-assembled from dendritic Dipeptides is approximately 10 A larger than that of structures assembled from dendritic alcohols. The increase of the D(pore) at the transition from dendritic alcohol to dendritic dipeptide is accompanied by a decreased solid angle of the building block. This trend is in agreement with previous pore size-solid angle dependences observed with different protective groups of the dipeptide and primary structures of the dendron. However, within the series of dendritic alcohols and dendritic Dipeptides with various n, the D(pore) increases when the solid angle increases. The results of these investigations together with those of previous studies on the role of dipeptide stereochemistry and protective groups on this self-assembly process provide the molecular principles required to program the construction of supramolecular helical pores with diameter controlled at the A level from a single dendritic dipeptide architecture. These principles are expected to be valid for libraries of dendritic Dipeptides based on dendrons and Dipeptides with various primary structures.
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programming the internal structure and stability of helical pores self assembled from dendritic Dipeptides via the protective groups of the peptide
Journal of the American Chemical Society, 2005Co-Authors: Virgil Percec, Andres E Dulcey, Monica Ilies, And Monika J Sienkowska, Mihai Peterca, Paul A. HeineyAbstract:The synthesis of dendritic Dipeptides (4-3,4-3,5)12G2−CH2−X−l-Tyr−l-Ala−OMe with X = Boc, Moc, and Ac; their self-assembly in bulk and in solution; and the structural and retrostructural analysis of their supramolecular helical porous assemblies are reported. The dimensions, structure, internal order, thermal stability of the supramolecular helical pores, and conformations of the dendron and supramolecular dendrimer are programmed by the nature of the protective groups of the dipeptide. The ability of the protective groups to program the structure of the helical pore reveals the simplest design strategy that complements the more complex strategies based on the architecture of the dendron, the stereochemistry, and the structure of the dipeptide.
Konrad Dabrowski - One of the best experts on this subject based on the ideXlab platform.
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Optimization of dipeptide–protein mixtures in experimental diet formulations for rainbow trout (Oncorhynchus mykiss) alevins
Aquaculture, 2006Co-Authors: Bendik F. Terjesen, Kyeong-jun Lee, Yongfang Zhang, Mark L. Failla, Konrad DabrowskiAbstract:Abstract It has previously been shown that diets in which the amino acid portion is based on synthetic Dipeptides result in positive growth of rainbow trout alevins. However, the protein-based diets used as a control performed significantly better. One objective of the present study was to identify a protein–dipeptide mixture ratio that results in comparable growth to a protein-based control, in alevins over the first 6 weeks of feeding. Seven diets were tested, including the casein–gelatin control, three diets with differing proportions of the casein–gelatin replaced with synthetic Dipeptides (50P, 75P and 100P), one diet based on free amino acids and one reference commercial diet. In the seventh diet, arginine-containing Dipeptides were withdrawn from the 100P dipeptide-based diet. To evaluate the diets, effects on growth, survival, feed intake and free amino acid (FAA) concentrations in muscle tissues were studied. The results on rainbow trout alevin performance using synthetic dipeptide (100P)-based diets resulted in a relative growth of 34% of the growth observed when alevins were fed the casein–gelatin control diet. The free amino acid (FAA)-based diet, however, resulted in a negative growth of the alevins. In contrast, a 1:1 ratio of synthetic Dipeptides to casein–gelatin (50P diet) resulted in similar growth as the casein–gelatin control diet fed fish. Furthermore, the 50P diet resulted in a survival that was not significantly different from that found when using a commercial diet, which showed the highest survival. The concentrations of indispensable FAA (IAA) in muscle were with few exceptions similar in the control and 50P group, while the 100P dipeptide- or free amino acid-based diet fed fish showed lower levels of free IAA in muscle. Alevins fed dipeptide-based diets without arginine (100P w/o Arg) showed high mortality within 2 weeks and negative or minimal growth. This dietary group was restarted at 2 and 4 weeks, and similar results were obtained. In conclusion, the present study indicates that a 50% replacement of the protein portion with synthetic Dipeptides is an acceptable diet formulation for rainbow trout alevins in terms of growth, survival and muscle levels of indispensable FAA. The effects of arginine-containing dipeptide withdrawal on fish growth and survival indicates that arginine is an indispensable amino acid in first-feeding alevins, despite their expression of the ornithine–urea cycle and related enzymes that may function in net de novo synthesis of arginine. The synthetic dipeptide diets used here were able to identify such limiting amino acids and may be further used to re-evaluate indispensable amino acid requirements in fish early life stages characterized with high growth.
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optimization of dipeptide protein mixtures in experimental diet formulations for rainbow trout oncorhynchus mykiss alevins
Aquaculture, 2006Co-Authors: Bendik F. Terjesen, Kyeong-jun Lee, Yongfang Zhang, Mark L. Failla, Konrad DabrowskiAbstract:Abstract It has previously been shown that diets in which the amino acid portion is based on synthetic Dipeptides result in positive growth of rainbow trout alevins. However, the protein-based diets used as a control performed significantly better. One objective of the present study was to identify a protein–dipeptide mixture ratio that results in comparable growth to a protein-based control, in alevins over the first 6 weeks of feeding. Seven diets were tested, including the casein–gelatin control, three diets with differing proportions of the casein–gelatin replaced with synthetic Dipeptides (50P, 75P and 100P), one diet based on free amino acids and one reference commercial diet. In the seventh diet, arginine-containing Dipeptides were withdrawn from the 100P dipeptide-based diet. To evaluate the diets, effects on growth, survival, feed intake and free amino acid (FAA) concentrations in muscle tissues were studied. The results on rainbow trout alevin performance using synthetic dipeptide (100P)-based diets resulted in a relative growth of 34% of the growth observed when alevins were fed the casein–gelatin control diet. The free amino acid (FAA)-based diet, however, resulted in a negative growth of the alevins. In contrast, a 1:1 ratio of synthetic Dipeptides to casein–gelatin (50P diet) resulted in similar growth as the casein–gelatin control diet fed fish. Furthermore, the 50P diet resulted in a survival that was not significantly different from that found when using a commercial diet, which showed the highest survival. The concentrations of indispensable FAA (IAA) in muscle were with few exceptions similar in the control and 50P group, while the 100P dipeptide- or free amino acid-based diet fed fish showed lower levels of free IAA in muscle. Alevins fed dipeptide-based diets without arginine (100P w/o Arg) showed high mortality within 2 weeks and negative or minimal growth. This dietary group was restarted at 2 and 4 weeks, and similar results were obtained. In conclusion, the present study indicates that a 50% replacement of the protein portion with synthetic Dipeptides is an acceptable diet formulation for rainbow trout alevins in terms of growth, survival and muscle levels of indispensable FAA. The effects of arginine-containing dipeptide withdrawal on fish growth and survival indicates that arginine is an indispensable amino acid in first-feeding alevins, despite their expression of the ornithine–urea cycle and related enzymes that may function in net de novo synthesis of arginine. The synthetic dipeptide diets used here were able to identify such limiting amino acids and may be further used to re-evaluate indispensable amino acid requirements in fish early life stages characterized with high growth.