The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Salam Al-karadaghi - One of the best experts on this subject based on the ideXlab platform.
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Metallation of the transition-state inhibitor N-methyl mesoporphyrin by ferrochelatase: implications for the catalytic reaction mechanism.
Journal of Molecular Biology, 2005Co-Authors: Stepan Shipovskov, Tobias Karlberg, Michel Fodje, Mattias D. Hansson, Gloria C. Ferreira, Mats Hansson, Curt T. Reimann, Salam Al-karadaghiAbstract:Insertion of metals into various tetrapyrroles is catalysed by a group of enzymes called chelatases, e.g. nickel, cobalt, magnesium and ferrochelatase. It has been proposed that catalytic Metallation includes distorting the porphyrin substrate by the enzyme towards a transition state-like geometry in which at least one of the pyrrole rings will be available for metal chelation. Here, we present a study of metal insertion into the transition-state inhibitor of protoporphyrin IX ferrochelatase, N-methyl mesoporphyrin (N-MeMP), by time-resolved crystallography and mass spectrometry with and without the presence of ferrochelatase. The results show that Metallation of N-MeMP has a very limited effect on the conformation of the residues that participate in porphyrin and metal binding. These findings support theoretical data, which indicate that product release is controlled largely by the strain created by metal insertion into the distorted porphyrin. The results suggest that, similar to noncatalytic Metallation of N-MeMP, the ferrochelatase-assisted Metallation depends on the ligand exchange rate for the respective metal. Moreover, ferrochelatase catalyses insertion of Cu(II) and Zn(II) into N-MeMP with a rate that is about 20 times faster than non-enzymatic Metallation in solution, suggesting that the catalytic strategy of ferrochelatase includes a stage of acceleration of the rate of ligand exchange for the metal substrate. The greater efficiency of N-MeMP Metallation by Cu(II), as compared to Zn(II), contrasts with the Km values for Zn(II), (17 mu M) and Cu(II) (170 mu M) obtained for Metallation of protoporphyrin IX. We suggest that this difference in metal specificity depends on the type of distortion imposed by the enzyme on protoporphyrin IX, which is different from the intrinsic non-planar distortion of N-MeMP. A mechanism of control of metal specificity by porphyrin distortion may be general for different chelatases, and may have common features with the mechanism of metal specificity in crown ethers.(c) 2005 Elsevier Ltd. All rights reserved. (Less)
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Metallation of the transition-state inhibitor N-methyl mesoporphyrin by ferrochelatase: implications for the catalytic reaction mechanism.
Journal of molecular biology, 2005Co-Authors: Stepan Shipovskov, Tobias Karlberg, Michel Fodje, Mattias D. Hansson, Gloria C. Ferreira, Mats Hansson, Curt T. Reimann, Salam Al-karadaghiAbstract:Insertion of metals into various tetrapyrroles is catalysed by a group of enzymes called chelatases, e.g. nickel, cobalt, magnesium and ferro-chelatase. It has been proposed that catalytic Metallation includes distorting the porphyrin substrate by the enzyme towards a transition state-like geometry in which at least one of the pyrrole rings will be available for metal chelation. Here, we present a study of metal insertion into the transition-state inhibitor of protoporphyrin IX ferrochelatase, N-methyl mesoporphyrin (N-MeMP), by time-resolved crystallography and mass spectrometry with and without the presence of ferrochelatase. The results show that Metallation of N-MeMP has a very limited effect on the conformation of the residues that participate in porphyrin and metal binding. These findings support theoretical data, which indicate that product release is controlled largely by the strain created by metal insertion into the distorted porphyrin. The results suggest that, similar to non-catalytic Metallation of N-MeMP, the ferrochelatase-assisted Metallation depends on the ligand exchange rate for the respective metal. Moreover, ferrochelatase catalyses insertion of Cu(II) and Zn(II) into N-MeMP with a rate that is about 20 times faster than non-enzymatic Metallation in solution, suggesting that the catalytic strategy of ferrochelatase includes a stage of acceleration of the rate of ligand exchange for the metal substrate. The greater efficiency of N-MeMP Metallation by Cu(II), as compared to Zn(II), contrasts with the K(m) values for Zn(II) (17 microM) and Cu(II) (170 microM) obtained for Metallation of protoporphyrin IX. We suggest that this difference in metal specificity depends on the type of distortion imposed by the enzyme on protoporphyrin IX, which is different from the intrinsic non-planar distortion of N-MeMP. A mechanism of control of metal specificity by porphyrin distortion may be general for different chelatases, and may have common features with the mechanism of metal specificity in crown ethers.
Christopher J. Sumby - One of the best experts on this subject based on the ideXlab platform.
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Probing post-synthetic Metallation in metal–organic frameworks: insights from X-ray crystallography
Chemical communications (Cambridge England), 2015Co-Authors: Witold M. Bloch, Alexandre Burgun, Christian J. Doonan, Christopher J. SumbyAbstract:For post-synthetic Metallation (PSMet) of a metal–organic framework (MOF, [Mn3(L2)(L′)] = 1) we show a solvent dependency for the form of the metallated product. PSMet of 1 with MnCl2 in ethanol leads to a single metal entity per coordinating site while acetonitrile yields a remarkably complex multiply metallated product; thus, determining the extent of Metallation requires an intimate understanding of the chemistry occurring in the MOF pores.
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probing post synthetic Metallation in metal organic frameworks insights from x ray crystallography
Chemical Communications, 2015Co-Authors: Witold M. Bloch, Alexandre Burgun, Christian J. Doonan, Christopher J. SumbyAbstract:For post-synthetic Metallation (PSMet) of a metal–organic framework (MOF, [Mn3(L2)(L′)] = 1) we show a solvent dependency for the form of the metallated product. PSMet of 1 with MnCl2 in ethanol leads to a single metal entity per coordinating site while acetonitrile yields a remarkably complex multiply metallated product; thus, determining the extent of Metallation requires an intimate understanding of the chemistry occurring in the MOF pores.
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capturing snapshots of post synthetic Metallation chemistry in metal organic frameworks
Nature Chemistry, 2014Co-Authors: Witold M. Bloch, Alexandre Burgun, Campbell J. Coghlan, Richmond Lee, Michelle L. Coote, Christian J. Doonan, Christopher J. SumbyAbstract:Post-synthetic Metallation is employed strategically to imbue metal-organic frameworks (MOFs) with enhanced performance characteristics. However, obtaining precise structural information for metal-centred reactions that take place within the pores of these materials has remained an elusive goal, because of issues with high symmetry in certain MOFs, lower initial crystallinity for some chemically robust MOFs, and the reduction in crystallinity that can result from carrying out post-synthetic reactions on parent crystals. Here, we report a new three-dimensional MOF possessing pore cavities that are lined with vacant di-pyrazole groups poised for post-synthetic Metallation. These Metallations occur quantitatively without appreciable loss of crystallinity, thereby enabling examination of the products by single-crystal X-ray diffraction. To illustrate the potential of this platform to garner fundamental insight into metal-catalysed reactions in porous solids we use single-crystal X-ray diffraction studies to structurally elucidate the reaction products of consecutive oxidative addition and methyl migration steps that occur within the pores of the Rh-metallated MOF, 1·[Rh(CO)2][Rh(CO)2Cl2].
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Capturing snapshots of post-synthetic Metallation chemistry in metal–organic frameworks
Nature chemistry, 2014Co-Authors: Witold M. Bloch, Alexandre Burgun, Campbell J. Coghlan, Richmond Lee, Michelle L. Coote, Christian J. Doonan, Christopher J. SumbyAbstract:Post-synthetic Metallation is employed strategically to imbue metal-organic frameworks (MOFs) with enhanced performance characteristics. However, obtaining precise structural information for metal-centred reactions that take place within the pores of these materials has remained an elusive goal, because of issues with high symmetry in certain MOFs, lower initial crystallinity for some chemically robust MOFs, and the reduction in crystallinity that can result from carrying out post-synthetic reactions on parent crystals. Here, we report a new three-dimensional MOF possessing pore cavities that are lined with vacant di-pyrazole groups poised for post-synthetic Metallation. These Metallations occur quantitatively without appreciable loss of crystallinity, thereby enabling examination of the products by single-crystal X-ray diffraction. To illustrate the potential of this platform to garner fundamental insight into metal-catalysed reactions in porous solids we use single-crystal X-ray diffraction studies to structurally elucidate the reaction products of consecutive oxidative addition and methyl migration steps that occur within the pores of the Rh-metallated MOF, 1·[Rh(CO)2][Rh(CO)2Cl2].
Stepan Shipovskov - One of the best experts on this subject based on the ideXlab platform.
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Metallation of the transition-state inhibitor N-methyl mesoporphyrin by ferrochelatase: implications for the catalytic reaction mechanism.
Journal of Molecular Biology, 2005Co-Authors: Stepan Shipovskov, Tobias Karlberg, Michel Fodje, Mattias D. Hansson, Gloria C. Ferreira, Mats Hansson, Curt T. Reimann, Salam Al-karadaghiAbstract:Insertion of metals into various tetrapyrroles is catalysed by a group of enzymes called chelatases, e.g. nickel, cobalt, magnesium and ferrochelatase. It has been proposed that catalytic Metallation includes distorting the porphyrin substrate by the enzyme towards a transition state-like geometry in which at least one of the pyrrole rings will be available for metal chelation. Here, we present a study of metal insertion into the transition-state inhibitor of protoporphyrin IX ferrochelatase, N-methyl mesoporphyrin (N-MeMP), by time-resolved crystallography and mass spectrometry with and without the presence of ferrochelatase. The results show that Metallation of N-MeMP has a very limited effect on the conformation of the residues that participate in porphyrin and metal binding. These findings support theoretical data, which indicate that product release is controlled largely by the strain created by metal insertion into the distorted porphyrin. The results suggest that, similar to noncatalytic Metallation of N-MeMP, the ferrochelatase-assisted Metallation depends on the ligand exchange rate for the respective metal. Moreover, ferrochelatase catalyses insertion of Cu(II) and Zn(II) into N-MeMP with a rate that is about 20 times faster than non-enzymatic Metallation in solution, suggesting that the catalytic strategy of ferrochelatase includes a stage of acceleration of the rate of ligand exchange for the metal substrate. The greater efficiency of N-MeMP Metallation by Cu(II), as compared to Zn(II), contrasts with the Km values for Zn(II), (17 mu M) and Cu(II) (170 mu M) obtained for Metallation of protoporphyrin IX. We suggest that this difference in metal specificity depends on the type of distortion imposed by the enzyme on protoporphyrin IX, which is different from the intrinsic non-planar distortion of N-MeMP. A mechanism of control of metal specificity by porphyrin distortion may be general for different chelatases, and may have common features with the mechanism of metal specificity in crown ethers.(c) 2005 Elsevier Ltd. All rights reserved. (Less)
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Metallation of the transition-state inhibitor N-methyl mesoporphyrin by ferrochelatase: implications for the catalytic reaction mechanism.
Journal of molecular biology, 2005Co-Authors: Stepan Shipovskov, Tobias Karlberg, Michel Fodje, Mattias D. Hansson, Gloria C. Ferreira, Mats Hansson, Curt T. Reimann, Salam Al-karadaghiAbstract:Insertion of metals into various tetrapyrroles is catalysed by a group of enzymes called chelatases, e.g. nickel, cobalt, magnesium and ferro-chelatase. It has been proposed that catalytic Metallation includes distorting the porphyrin substrate by the enzyme towards a transition state-like geometry in which at least one of the pyrrole rings will be available for metal chelation. Here, we present a study of metal insertion into the transition-state inhibitor of protoporphyrin IX ferrochelatase, N-methyl mesoporphyrin (N-MeMP), by time-resolved crystallography and mass spectrometry with and without the presence of ferrochelatase. The results show that Metallation of N-MeMP has a very limited effect on the conformation of the residues that participate in porphyrin and metal binding. These findings support theoretical data, which indicate that product release is controlled largely by the strain created by metal insertion into the distorted porphyrin. The results suggest that, similar to non-catalytic Metallation of N-MeMP, the ferrochelatase-assisted Metallation depends on the ligand exchange rate for the respective metal. Moreover, ferrochelatase catalyses insertion of Cu(II) and Zn(II) into N-MeMP with a rate that is about 20 times faster than non-enzymatic Metallation in solution, suggesting that the catalytic strategy of ferrochelatase includes a stage of acceleration of the rate of ligand exchange for the metal substrate. The greater efficiency of N-MeMP Metallation by Cu(II), as compared to Zn(II), contrasts with the K(m) values for Zn(II) (17 microM) and Cu(II) (170 microM) obtained for Metallation of protoporphyrin IX. We suggest that this difference in metal specificity depends on the type of distortion imposed by the enzyme on protoporphyrin IX, which is different from the intrinsic non-planar distortion of N-MeMP. A mechanism of control of metal specificity by porphyrin distortion may be general for different chelatases, and may have common features with the mechanism of metal specificity in crown ethers.
Samar S Hasnain - One of the best experts on this subject based on the ideXlab platform.
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variable Metallation of human superoxide dismutase atomic resolution crystal structures of cu zn zn zn and as isolated wild type enzymes
Journal of Molecular Biology, 2006Co-Authors: Richard W Strange, Svetlana V Antonyuk, Michael A Hough, Peter A Doucette, Joan Selverstone Valentine, Samar S HasnainAbstract:Human Cu-Zn superoxide dismutase (SOD1) protects cells from the effects of oxidative stress. Mutations in SOD1 are linked to the familial form of amyotrophic lateral sclerosis. Several hypotheses for their toxicity involve the mis-Metallation of the enzyme. We present atomic-resolution crystal structures and biophysical data for human SOD1 in three Metallation states: Zn-Zn, Cu-Zn and as-isolated. These data represent the first atomic-resolution structures for human SOD1, the first structure of a reduced SOD1, and the first structure of a fully Zn-substituted SOD1 enzyme. Recombinantly expressed as-isolated SOD1 contains a mixture of Zn and Cu at the Cu-binding site. The Zn-Zn structure appears to be at least as stable as the correctly (Cu-Zn) metallated enzyme. These data raise the possibility that in a cellular environment with low availability of free copper, Zn-Zn may be the preferred Metallation state of SOD1 prior to its interaction with the copper chaperone.
Witold M. Bloch - One of the best experts on this subject based on the ideXlab platform.
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Probing post-synthetic Metallation in metal–organic frameworks: insights from X-ray crystallography
Chemical communications (Cambridge England), 2015Co-Authors: Witold M. Bloch, Alexandre Burgun, Christian J. Doonan, Christopher J. SumbyAbstract:For post-synthetic Metallation (PSMet) of a metal–organic framework (MOF, [Mn3(L2)(L′)] = 1) we show a solvent dependency for the form of the metallated product. PSMet of 1 with MnCl2 in ethanol leads to a single metal entity per coordinating site while acetonitrile yields a remarkably complex multiply metallated product; thus, determining the extent of Metallation requires an intimate understanding of the chemistry occurring in the MOF pores.
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probing post synthetic Metallation in metal organic frameworks insights from x ray crystallography
Chemical Communications, 2015Co-Authors: Witold M. Bloch, Alexandre Burgun, Christian J. Doonan, Christopher J. SumbyAbstract:For post-synthetic Metallation (PSMet) of a metal–organic framework (MOF, [Mn3(L2)(L′)] = 1) we show a solvent dependency for the form of the metallated product. PSMet of 1 with MnCl2 in ethanol leads to a single metal entity per coordinating site while acetonitrile yields a remarkably complex multiply metallated product; thus, determining the extent of Metallation requires an intimate understanding of the chemistry occurring in the MOF pores.
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capturing snapshots of post synthetic Metallation chemistry in metal organic frameworks
Nature Chemistry, 2014Co-Authors: Witold M. Bloch, Alexandre Burgun, Campbell J. Coghlan, Richmond Lee, Michelle L. Coote, Christian J. Doonan, Christopher J. SumbyAbstract:Post-synthetic Metallation is employed strategically to imbue metal-organic frameworks (MOFs) with enhanced performance characteristics. However, obtaining precise structural information for metal-centred reactions that take place within the pores of these materials has remained an elusive goal, because of issues with high symmetry in certain MOFs, lower initial crystallinity for some chemically robust MOFs, and the reduction in crystallinity that can result from carrying out post-synthetic reactions on parent crystals. Here, we report a new three-dimensional MOF possessing pore cavities that are lined with vacant di-pyrazole groups poised for post-synthetic Metallation. These Metallations occur quantitatively without appreciable loss of crystallinity, thereby enabling examination of the products by single-crystal X-ray diffraction. To illustrate the potential of this platform to garner fundamental insight into metal-catalysed reactions in porous solids we use single-crystal X-ray diffraction studies to structurally elucidate the reaction products of consecutive oxidative addition and methyl migration steps that occur within the pores of the Rh-metallated MOF, 1·[Rh(CO)2][Rh(CO)2Cl2].
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Capturing snapshots of post-synthetic Metallation chemistry in metal–organic frameworks
Nature chemistry, 2014Co-Authors: Witold M. Bloch, Alexandre Burgun, Campbell J. Coghlan, Richmond Lee, Michelle L. Coote, Christian J. Doonan, Christopher J. SumbyAbstract:Post-synthetic Metallation is employed strategically to imbue metal-organic frameworks (MOFs) with enhanced performance characteristics. However, obtaining precise structural information for metal-centred reactions that take place within the pores of these materials has remained an elusive goal, because of issues with high symmetry in certain MOFs, lower initial crystallinity for some chemically robust MOFs, and the reduction in crystallinity that can result from carrying out post-synthetic reactions on parent crystals. Here, we report a new three-dimensional MOF possessing pore cavities that are lined with vacant di-pyrazole groups poised for post-synthetic Metallation. These Metallations occur quantitatively without appreciable loss of crystallinity, thereby enabling examination of the products by single-crystal X-ray diffraction. To illustrate the potential of this platform to garner fundamental insight into metal-catalysed reactions in porous solids we use single-crystal X-ray diffraction studies to structurally elucidate the reaction products of consecutive oxidative addition and methyl migration steps that occur within the pores of the Rh-metallated MOF, 1·[Rh(CO)2][Rh(CO)2Cl2].