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Kenji Takahashi - One of the best experts on this subject based on the ideXlab platform.
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crystal structure of ribonuclease t1 carboxymethylated at glu58 in complex with 2 gmp
Biochemistry, 1996Co-Authors: Kohki Ishikawa, Eiichiro Suzuki, Masaru Tanokura, Kenji TakahashiAbstract:The Carboxymethylation of RNase T1 at the γ-carboxyl group of Glu58 leads to a complete loss of the enzymatic activity while it retains substrate-binding ability. Accompanying the Carboxymethylation, RNase T1 undergoes a remarkable thermal stabilization of 9 °C in the melting temperature (Tm). In order to clarify the inactivation and stabilization mechanisms of RNase T1 by Carboxymethylation, the crystal structure of carboxymethylated RNase T1 (CM-RNase T1) complexed with 2‘-GMP was determined at 1.8 A resolution. The structure, including 79 water molecules and two Na+, was refined to an R factor of 0.194 with 10 354 reflections >1σ(F). The carboxyl group of CM-Glu58, which locates in the active site, occupies almost the same position as the phosphate group of 2‘-GMP in the crystal structure of intact RNase T1·2‘-GMP complex. Therefore, the phosphate group of 2‘-GMP cannot locate in the active site but protrudes toward the solvent. This forces 2‘-GMP to adopt an anti form, which contrasts with the syn for...
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thermal stabilization of ribonuclease t1 by Carboxymethylation at glu 58 as revealed by 1h nuclear magnetic resonance spectroscopy
FEBS Letters, 1994Co-Authors: Masaki Kojima, Eiichiro Suzuki, Masaru Tanokura, Toshimi Mizukoshi, Hiroshi Miyano, Kenji TakahashiAbstract:Ribonuclease T1 (RNase T1) carboxymethylated at the γ-carboxyl group of Glu-58 with iodoacetic acid is known to be completely inactive while it retains an almost full substrate-binding ability. In order to further clarify the effects of the Carboxymethylation, the thermal stabilities of intact and Glu-58-carboxymethylated (CM-) RNase T1 were compared by measuring 1H NMR spectra at various temperatures. The transition curves of unfolding were obtained by plotting, as a function of temperature, the peak areas for the α and δ protons of Asn-81 and Ile-90 respectively, which are well apart from each other in the three-dimensional structure of the enzyme. For each of intact and CM-RNase T1, the transition curve of the Asn-81 α proton was identical with that of the Ile-90 δ methyl protons, suggesting that the thermal unfolding occurred simultaneously in every part of the molecule of CM-RNase T1 as well as of intact RNase T1. The midpoint of unfolding was 52°C for intact RNase T1, and was increased by 9°C upon Carboxymethylation at Glu-58. This marked stabilization by Carboxymethylation is thought to be due to formation of a salt bridge between the introduced carboxymethyl group and the neighboring guanidium group of Arg-77.
Steffen Fischer - One of the best experts on this subject based on the ideXlab platform.
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impact of pre treatments on properties of lignocelluloses and their accessibility for a subsequent Carboxymethylation
Carbohydrate Polymers, 2017Co-Authors: Katja Heise, Christine Rossberg, Juliane Stratz, Christian Baurich, Erica Brendler, Harald Keller, Steffen FischerAbstract:In this issue, different chemical (alkaline and sulfite pulping, ozonolysis) and mechanical (vibratory ball milling) pre-treatments were utilized for activating wheat straw and beech sawdust prior to Carboxymethylation. Detailed analysis by a range of methods, including Klason-lignin, cellulose and hemicellulose quantification, Powder-X-ray diffraction (PXRD) and attenuated total reflection (ATR) IR spectroscopy, enabled the investigation of material alterations. Subsequently, Carboxymethylation was carried out with both untreated and activated materials, allowing the evaluation of activation steps by determining degrees of substitution with carboxymethyl groups (DSCM). Moreover, Carboxymethylation conditions were optimized, realizing high DSCM of up to 1.05. Results further revealed that ball milling enhanced the subsequent conversion; whereas chemical pre-treatments did not effectively increase material accessibilities. Further studies on chemically untreated materials emphasized that a highly reactive surface was already generated in the course of the Carboxymethylation, inter alia through the concomitant dissolution of matrix components.
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evaluation of molten inorganic salt hydrates as reaction medium for the esterification of cellulose
Cellulose, 2010Co-Authors: Katrin Thummler, Steffen Fischer, Jana Peters, Tim Liebert, Thomas HeinzeAbstract:Molten inorganic salt hydrates are highly efficient solvents forcellulose. The Carboxymethylation of the polymer dissolved in this new group ofcellulose solvents was investigated. The homogeneous Carboxymethylation ofcellulose in molten LiClO4•3H2O using sodiummonochloroacetate in the presence of NaOH is possible. The formation of CMC wasconfirmed by FT- Raman spectroscopy. Structure analysis by means of HPLC afterchain degradation showed the formation of CMC with a DS of 2 after a shortreaction time of 4 h. The derivatives exhibit a statisticaldistribution of substituents along the polymer chain if prepared in moltenLiClO4•3H2O as solvent. A substituent distributioninthe order C-6 > C-2 ≈ C-3 for anhydroglucose units (AGU) was concludedfrom 1H-NMR measurements. The synthesis of CMC in the swellingmediumLiCl•xH2O (2 ≤ x ≤ 5) yields polymers with astatistical distribution of functional groups along the chain. The watercontentof the salt melts has a dramatic influence on the DSCMC.
Mário Antônio Alves Da Cunha - One of the best experts on this subject based on the ideXlab platform.
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Fungal Exocellular (1-6)-β-d-glucan: Carboxymethylation, Characterization, and Antioxidant Activity
International Journal of Molecular Sciences, 2019Co-Authors: Thais Vanessa Theis, Vidiany Aparecida Queiroz Santos, Patrícia Appelt, Aneli M. Barbosa-dekker, Vaclav Vetvicka, Robert F H Dekker, Mário Antônio Alves Da CunhaAbstract:Exocellular (1→6)-β-d-glucan (lasiodiplodan) produced by the fungus Lasiodiplodia theobromae MMPI was derivatized by Carboxymethylation using different concentrations of a derivatizing agent. Lasiodiplodan was derivatized by Carboxymethylation in an attempt to increase its solubility and enhance its biological activities. Carboxymethylglucans with degrees of substitution (DS) of 0.32, 0.47, 0.51, 0.58, and 0.68 were produced and characterized. FTIR analysis showed a band of strong intensity at 1600 cm−1 and an absorption band at 1421 cm−1, resulting from asymmetric and symmetrical stretching vibrations, respectively, of the carboxymethyl group COO- in the carboxymethylated samples. Thermal analysis showed that native lasiodiplodan (LN) and carboxymethylated derivatives (LC) exhibited thermal stability up to 200–210 °C. X-ray diffractometry demonstrated that both native and carboxymethylated lasiodiplodan presented predominantly an amorphous nature. Scanning electron microscopy revealed that Carboxymethylation promoted morphological changes in the biopolymer and increased porosity, and alveolar structures were observed along the surface. The introduction of carboxymethyl groups in the macromolecule promoted increased solubility and potentiated the hydroxyl radical-scavenging activity, suggesting a correlation between degree of substitution and antioxidant activity.
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exocellular 1 6 β d glucan lasiodiplodan Carboxymethylation thermal behavior antioxidant and antimicrobial activity
American Journal of Immunology, 2017Co-Authors: Thais Vanessa Theis, Vidiany Aparecida Queiroz Santos, Robert F H Dekker, Aneli M. Barbosa, Gabrielle Cristina Calegari, Henrique Emilio Zorel, Mário Antônio Alves Da CunhaAbstract:β-Glucans are biomacromolecules of industrial interest for its biological and technological properties, including ability to modify the rheology of food systems and different biological functionalities. In this study, lasiodiplodan an exocellular polysaccharide of the (1→6)-β-D-glucan type produced by the fungus Lasiodiplodia theobromae MMPI was obtained in a bench-scale bioreactor operated in discontinuous mode. Lasiodiplodan produced was derivatized by Carboxymethylation and characterized by Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetry and Differential Thermal Analysis (TG-DTA), X-Ray Diffraction (XRD), scan electron microscopy (SEM) and their antioxidant and antimicrobial potential also was assessed. Two strong absorption bands in the regions of 1422 to 1598 cm-1, resulting from symmetric and asymmetric stretching vibrations of the -COO- group respectively, were observed in the FT-IR spectrum of the derivatized sample and indicated the Carboxymethylation of the macromolecule. TG-DTA curves indicated that native (LAS-N) and carboxymethylated (LAS-C) lasiodiplodan did not suffer significant changes in relation to the heating rates. Native and carboxymethylated lasiodiplodan demonstrated high thermal stability considering the usual standards of the pharmaceutical industry. The final temperature of thermal decomposition increased when the heating rate was increased and less number of steps for thermal decomposition was observed when air was substituted for nitrogen. XRD analysis showed the LAS-N and LAS-C have no crystalline structure, but Carboxymethylation led to the arising of regions with certain molecular orientation in biopolymer structure. SEM analysis showed that the Carboxymethylation promoted changes in biopolymer macrostructure, including breaking of the polymeric structure and arising of bubbles on the surface area. Carboxymethylation contributed to improving the polysaccharide's antioxidant capacity and LAS-C demonstrated antimicrobial activity against Candida tropicalis.
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Exocellular (1→6)-β-D-Glucan (Lasiodiplodan): Carboxymethylation, Thermal Behavior, Antioxidant and Antimicrobial Activity
American Journal of Immunology, 2017Co-Authors: Thais Vanessa Theis, Vidiany Aparecida Queiroz Santos, Robert F H Dekker, Aneli M. Barbosa, Gabrielle Cristina Calegari, Henrique Emilio Zorel Junior, Mário Antônio Alves Da CunhaAbstract:β-Glucans are biomacromolecules of industrial interest for its biological and technological properties, including ability to modify the rheology of food systems and different biological functionalities. In this study, lasiodiplodan an exocellular polysaccharide of the (1→6)-β-D-glucan type produced by the fungus Lasiodiplodia theobromae MMPI was obtained in a bench-scale bioreactor operated in discontinuous mode. Lasiodiplodan produced was derivatized by Carboxymethylation and characterized by Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetry and Differential Thermal Analysis (TG-DTA), X-Ray Diffraction (XRD), scan electron microscopy (SEM) and their antioxidant and antimicrobial potential also was assessed. Two strong absorption bands in the regions of 1422 to 1598 cm-1, resulting from symmetric and asymmetric stretching vibrations of the -COO- group respectively, were observed in the FT-IR spectrum of the derivatized sample and indicated the Carboxymethylation of the macromolecule. TG-DTA curves indicated that native (LAS-N) and carboxymethylated (LAS-C) lasiodiplodan did not suffer significant changes in relation to the heating rates. Native and carboxymethylated lasiodiplodan demonstrated high thermal stability considering the usual standards of the pharmaceutical industry. The final temperature of thermal decomposition increased when the heating rate was increased and less number of steps for thermal decomposition was observed when air was substituted for nitrogen. XRD analysis showed the LAS-N and LAS-C have no crystalline structure, but Carboxymethylation led to the arising of regions with certain molecular orientation in biopolymer structure. SEM analysis showed that the Carboxymethylation promoted changes in biopolymer macrostructure, including breaking of the polymeric structure and arising of bubbles on the surface area. Carboxymethylation contributed to improving the polysaccharide's antioxidant capacity and LAS-C demonstrated antimicrobial activity against Candida tropicalis.
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Carboxymethylation of 1 6 β glucan lasiodiplodan preparation characterization and antioxidant evaluation
Carbohydrate Polymers, 2015Co-Authors: Francini Yumi Kagimura, Thais Vanessa Theis, Mário Antônio Alves Da Cunha, Robert F H Dekker, Carlos Ricardo Maneck Malfatti, Aneli M. Barbosa, Sirlei Dias Teixeira, Kahlil Schwanka SaloméAbstract:Abstract d -Glucans possess immunomodulatory activities and potential for the development of new therapeutic agents. Biological activities can be enhanced in these biopolymers through chemical derivatization, e.g., Carboxymethylation. This work presents the Carboxymethylation, characterization and the evaluation of antioxidant activities of the exocellular (1 → 6)-β- d -glucan produced by Lasiodiplodia theobromae MMPI. Thermal analysis indicated that the native and carboxymethylated polysaccharides presented four stages of mass-loss. The first stage occurred at 125 °C (loss of water) with two consecutive events of mass loss (200–400 °C) attributed to polymer degradation and the fourth stage between 425 and 620 °C (final decomposition). Scanning electron microscopy analysis indicated that the gross morphological features of lasiodiplodan were ruptured following Carboxymethylation. X-ray diffractometry analysis demonstrated that the native and carboxymethylated polysaccharides presented a non-crystalline structure. Carboxymethylation contributed to improving the polysaccharide's water solubility and antioxidant capacity.
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Carboxymethylation of (1 → 6)-β-glucan (lasiodiplodan): Preparation, characterization and antioxidant evaluation.
Carbohydrate polymers, 2015Co-Authors: Francini Yumi Kagimura, Thais Vanessa Theis, Mário Antônio Alves Da Cunha, Robert F H Dekker, Carlos Ricardo Maneck Malfatti, Aneli M. Barbosa, Sirlei Dias Teixeira, Kahlil Schwanka SaloméAbstract:Abstract d -Glucans possess immunomodulatory activities and potential for the development of new therapeutic agents. Biological activities can be enhanced in these biopolymers through chemical derivatization, e.g., Carboxymethylation. This work presents the Carboxymethylation, characterization and the evaluation of antioxidant activities of the exocellular (1 → 6)-β- d -glucan produced by Lasiodiplodia theobromae MMPI. Thermal analysis indicated that the native and carboxymethylated polysaccharides presented four stages of mass-loss. The first stage occurred at 125 °C (loss of water) with two consecutive events of mass loss (200–400 °C) attributed to polymer degradation and the fourth stage between 425 and 620 °C (final decomposition). Scanning electron microscopy analysis indicated that the gross morphological features of lasiodiplodan were ruptured following Carboxymethylation. X-ray diffractometry analysis demonstrated that the native and carboxymethylated polysaccharides presented a non-crystalline structure. Carboxymethylation contributed to improving the polysaccharide's water solubility and antioxidant capacity.
Eiichiro Suzuki - One of the best experts on this subject based on the ideXlab platform.
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crystal structure of ribonuclease t1 carboxymethylated at glu58 in complex with 2 gmp
Biochemistry, 1996Co-Authors: Kohki Ishikawa, Eiichiro Suzuki, Masaru Tanokura, Kenji TakahashiAbstract:The Carboxymethylation of RNase T1 at the γ-carboxyl group of Glu58 leads to a complete loss of the enzymatic activity while it retains substrate-binding ability. Accompanying the Carboxymethylation, RNase T1 undergoes a remarkable thermal stabilization of 9 °C in the melting temperature (Tm). In order to clarify the inactivation and stabilization mechanisms of RNase T1 by Carboxymethylation, the crystal structure of carboxymethylated RNase T1 (CM-RNase T1) complexed with 2‘-GMP was determined at 1.8 A resolution. The structure, including 79 water molecules and two Na+, was refined to an R factor of 0.194 with 10 354 reflections >1σ(F). The carboxyl group of CM-Glu58, which locates in the active site, occupies almost the same position as the phosphate group of 2‘-GMP in the crystal structure of intact RNase T1·2‘-GMP complex. Therefore, the phosphate group of 2‘-GMP cannot locate in the active site but protrudes toward the solvent. This forces 2‘-GMP to adopt an anti form, which contrasts with the syn for...
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thermal stabilization of ribonuclease t1 by Carboxymethylation at glu 58 as revealed by 1h nuclear magnetic resonance spectroscopy
FEBS Letters, 1994Co-Authors: Masaki Kojima, Eiichiro Suzuki, Masaru Tanokura, Toshimi Mizukoshi, Hiroshi Miyano, Kenji TakahashiAbstract:Ribonuclease T1 (RNase T1) carboxymethylated at the γ-carboxyl group of Glu-58 with iodoacetic acid is known to be completely inactive while it retains an almost full substrate-binding ability. In order to further clarify the effects of the Carboxymethylation, the thermal stabilities of intact and Glu-58-carboxymethylated (CM-) RNase T1 were compared by measuring 1H NMR spectra at various temperatures. The transition curves of unfolding were obtained by plotting, as a function of temperature, the peak areas for the α and δ protons of Asn-81 and Ile-90 respectively, which are well apart from each other in the three-dimensional structure of the enzyme. For each of intact and CM-RNase T1, the transition curve of the Asn-81 α proton was identical with that of the Ile-90 δ methyl protons, suggesting that the thermal unfolding occurred simultaneously in every part of the molecule of CM-RNase T1 as well as of intact RNase T1. The midpoint of unfolding was 52°C for intact RNase T1, and was increased by 9°C upon Carboxymethylation at Glu-58. This marked stabilization by Carboxymethylation is thought to be due to formation of a salt bridge between the introduced carboxymethyl group and the neighboring guanidium group of Arg-77.
Masaru Tanokura - One of the best experts on this subject based on the ideXlab platform.
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crystal structure of ribonuclease t1 carboxymethylated at glu58 in complex with 2 gmp
Biochemistry, 1996Co-Authors: Kohki Ishikawa, Eiichiro Suzuki, Masaru Tanokura, Kenji TakahashiAbstract:The Carboxymethylation of RNase T1 at the γ-carboxyl group of Glu58 leads to a complete loss of the enzymatic activity while it retains substrate-binding ability. Accompanying the Carboxymethylation, RNase T1 undergoes a remarkable thermal stabilization of 9 °C in the melting temperature (Tm). In order to clarify the inactivation and stabilization mechanisms of RNase T1 by Carboxymethylation, the crystal structure of carboxymethylated RNase T1 (CM-RNase T1) complexed with 2‘-GMP was determined at 1.8 A resolution. The structure, including 79 water molecules and two Na+, was refined to an R factor of 0.194 with 10 354 reflections >1σ(F). The carboxyl group of CM-Glu58, which locates in the active site, occupies almost the same position as the phosphate group of 2‘-GMP in the crystal structure of intact RNase T1·2‘-GMP complex. Therefore, the phosphate group of 2‘-GMP cannot locate in the active site but protrudes toward the solvent. This forces 2‘-GMP to adopt an anti form, which contrasts with the syn for...
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thermal stabilization of ribonuclease t1 by Carboxymethylation at glu 58 as revealed by 1h nuclear magnetic resonance spectroscopy
FEBS Letters, 1994Co-Authors: Masaki Kojima, Eiichiro Suzuki, Masaru Tanokura, Toshimi Mizukoshi, Hiroshi Miyano, Kenji TakahashiAbstract:Ribonuclease T1 (RNase T1) carboxymethylated at the γ-carboxyl group of Glu-58 with iodoacetic acid is known to be completely inactive while it retains an almost full substrate-binding ability. In order to further clarify the effects of the Carboxymethylation, the thermal stabilities of intact and Glu-58-carboxymethylated (CM-) RNase T1 were compared by measuring 1H NMR spectra at various temperatures. The transition curves of unfolding were obtained by plotting, as a function of temperature, the peak areas for the α and δ protons of Asn-81 and Ile-90 respectively, which are well apart from each other in the three-dimensional structure of the enzyme. For each of intact and CM-RNase T1, the transition curve of the Asn-81 α proton was identical with that of the Ile-90 δ methyl protons, suggesting that the thermal unfolding occurred simultaneously in every part of the molecule of CM-RNase T1 as well as of intact RNase T1. The midpoint of unfolding was 52°C for intact RNase T1, and was increased by 9°C upon Carboxymethylation at Glu-58. This marked stabilization by Carboxymethylation is thought to be due to formation of a salt bridge between the introduced carboxymethyl group and the neighboring guanidium group of Arg-77.