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Tapan Kumar Chaudhuri - One of the best experts on this subject based on the ideXlab platform.

  • Structural stability and unfolding transition of β-glucosidases: a comparative investigation on isozymes from a thermo-tolerant yeast
    European Biophysics Journal, 2011
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan Kumar Chaudhuri
    Abstract:

    The folding of proteins in the milieu of the cellular environment involves various interactions among the residues of the polypeptide chain and the microenvironment where it resides. These interactions are responsible for stabilizing the protein molecule, and disruption of the same provides information about the stability of the molecule. β-Glucosidase isozymes, despite having high homology in their primary and tertiary designs, show deviations in their properties such as unfolding, refolding, and stability. In a comparative study on two large cell-wall-bound isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from a thermo-tolerant yeast, Pichia etchellsii, we have investigated guanidine hydrochloride (GdnHCl)-induced, alkali-induced, and thermal-unfolding transitions using CD and fluorescence spectroscopy and high sensitivity differential scanning calorimetry. Using spectral parameters (MRE 222 nm) to monitor the conformational transitions of the GdnHCl-induced unfolding phenomenon, it was observed that the midpoints of unfolding, apparent C _m, occurred at 1.2 M ± 0.05 and 0.8 M ± 0.03 GdnHCl, respectively, for BGLI and BglII. The alkali-induced unfolding process indicated that BGLI showed a mid-transition point at pH 11 ± 0.17, while for BglII it was at pH 10 ± 0.40, further indicating BGLI to be more stable to alkali denaturation than BglII. In the case of thermal unfolding, the midpoint of transition was observed at 63 ± 0.12°C for BGLI and at 58 ± 0.55°C for BglII. Analysis by high sensitivity differential scanning calorimeter supported the unfolding data in which BGLI showed higher melting temperature, T _m, (56.07°C ± 0.34) than BglII (54.02°C ± 0.36). Our results clearly indicate that BGLI is structurally more rigid and stable than BglII.

  • Structural stability and unfolding transition of β-glucosidases: a comparative investigation on isozymes from a thermo-tolerant yeast.
    European Biophysics Journal, 2011
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan Kumar Chaudhuri
    Abstract:

    The folding of proteins in the milieu of the cellular environment involves various interactions among the residues of the polypeptide chain and the microenvironment where it resides. These interactions are responsible for stabilizing the protein molecule, and disruption of the same provides information about the stability of the molecule. β-Glucosidase isozymes, despite having high homology in their primary and tertiary designs, show deviations in their properties such as unfolding, refolding, and stability. In a comparative study on two large cell-wall-bound isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from a thermo-tolerant yeast, Pichia etchellsii, we have investigated guanidine hydrochloride (GdnHCl)-induced, alkali-induced, and thermal-unfolding transitions using CD and fluorescence spectroscopy and high sensitivity differential scanning calorimetry. Using spectral parameters (MRE 222 nm) to monitor the conformational transitions of the GdnHCl-induced unfolding phenomenon, it was observed that the midpoints of unfolding, apparent C m, occurred at 1.2 M ± 0.05 and 0.8 M ± 0.03 GdnHCl, respectively, for BGLI and BglII. The alkali-induced unfolding process indicated that BGLI showed a mid-transition point at pH 11 ± 0.17, while for BglII it was at pH 10 ± 0.40, further indicating BGLI to be more stable to alkali denaturation than BglII. In the case of thermal unfolding, the midpoint of transition was observed at 63 ± 0.12°C for BGLI and at 58 ± 0.55°C for BglII. Analysis by high sensitivity differential scanning calorimeter supported the unfolding data in which BGLI showed higher melting temperature, T m, (56.07°C ± 0.34) than BglII (54.02°C ± 0.36). Our results clearly indicate that BGLI is structurally more rigid and stable than BglII.

Mohammad Asif Shah - One of the best experts on this subject based on the ideXlab platform.

  • Marginal stability drives irreversible unfolding of large multi-domain family 3 glycosylhydrolases from thermo-tolerant yeast.
    International Journal of Biological Macromolecules, 2018
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan K. Chaudhuri
    Abstract:

    Abstract Protein folding is an extremely complex and fast, yet perfectly defined process, involving interplay of many intra and inter-molecular forces. In vitro , these molecular interactions are reversible for many proteins e.g. , smaller and monomeric, organized into single domains. However, refolding of larger multi-domain/multimeric proteins is much more complicated, proceeds in a hierarchal way and is often irreversible. In a comparative study on two large, multi-domain and multimeric isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from Pichia etchellsii , we studied spontaneous and assisted refolding under three denaturing conditions viz . GdnHCl, alkaline pH and heat. During refolding, higher refolding yields were obtained for BglII in case of pH induced unfolding (13.89% ± 0.25) than BGLI (6% ± 0.85) while for GdnHCl induced unfolding, refolding was marginal (BGLI = 5% ± 0.5; BglII = 6% ± 0.69). Thermal unfolding was irreversible while assisted refolding also showed little structural gain for both proteins. When the apparent free energies of unfolding (ΔG U app ) were calculated from GdnHCl unfolding data, their values were strikingly found to be lower (BGLI ΔG U app  = 3.02 kcal/mol; BglII ΔG U app  = 2.99 kcal/mol) than reported for globular (ΔG U  = 5–15 kcal/mol)/multimeric proteins (ΔG U  = 23–29 kcal/mol) indicating marginal stability results in low refolding.

  • Structural stability and unfolding transition of β-glucosidases: a comparative investigation on isozymes from a thermo-tolerant yeast
    European Biophysics Journal, 2011
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan Kumar Chaudhuri
    Abstract:

    The folding of proteins in the milieu of the cellular environment involves various interactions among the residues of the polypeptide chain and the microenvironment where it resides. These interactions are responsible for stabilizing the protein molecule, and disruption of the same provides information about the stability of the molecule. β-Glucosidase isozymes, despite having high homology in their primary and tertiary designs, show deviations in their properties such as unfolding, refolding, and stability. In a comparative study on two large cell-wall-bound isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from a thermo-tolerant yeast, Pichia etchellsii, we have investigated guanidine hydrochloride (GdnHCl)-induced, alkali-induced, and thermal-unfolding transitions using CD and fluorescence spectroscopy and high sensitivity differential scanning calorimetry. Using spectral parameters (MRE 222 nm) to monitor the conformational transitions of the GdnHCl-induced unfolding phenomenon, it was observed that the midpoints of unfolding, apparent C _m, occurred at 1.2 M ± 0.05 and 0.8 M ± 0.03 GdnHCl, respectively, for BGLI and BglII. The alkali-induced unfolding process indicated that BGLI showed a mid-transition point at pH 11 ± 0.17, while for BglII it was at pH 10 ± 0.40, further indicating BGLI to be more stable to alkali denaturation than BglII. In the case of thermal unfolding, the midpoint of transition was observed at 63 ± 0.12°C for BGLI and at 58 ± 0.55°C for BglII. Analysis by high sensitivity differential scanning calorimeter supported the unfolding data in which BGLI showed higher melting temperature, T _m, (56.07°C ± 0.34) than BglII (54.02°C ± 0.36). Our results clearly indicate that BGLI is structurally more rigid and stable than BglII.

  • Structural stability and unfolding transition of β-glucosidases: a comparative investigation on isozymes from a thermo-tolerant yeast.
    European Biophysics Journal, 2011
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan Kumar Chaudhuri
    Abstract:

    The folding of proteins in the milieu of the cellular environment involves various interactions among the residues of the polypeptide chain and the microenvironment where it resides. These interactions are responsible for stabilizing the protein molecule, and disruption of the same provides information about the stability of the molecule. β-Glucosidase isozymes, despite having high homology in their primary and tertiary designs, show deviations in their properties such as unfolding, refolding, and stability. In a comparative study on two large cell-wall-bound isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from a thermo-tolerant yeast, Pichia etchellsii, we have investigated guanidine hydrochloride (GdnHCl)-induced, alkali-induced, and thermal-unfolding transitions using CD and fluorescence spectroscopy and high sensitivity differential scanning calorimetry. Using spectral parameters (MRE 222 nm) to monitor the conformational transitions of the GdnHCl-induced unfolding phenomenon, it was observed that the midpoints of unfolding, apparent C m, occurred at 1.2 M ± 0.05 and 0.8 M ± 0.03 GdnHCl, respectively, for BGLI and BglII. The alkali-induced unfolding process indicated that BGLI showed a mid-transition point at pH 11 ± 0.17, while for BglII it was at pH 10 ± 0.40, further indicating BGLI to be more stable to alkali denaturation than BglII. In the case of thermal unfolding, the midpoint of transition was observed at 63 ± 0.12°C for BGLI and at 58 ± 0.55°C for BglII. Analysis by high sensitivity differential scanning calorimeter supported the unfolding data in which BGLI showed higher melting temperature, T m, (56.07°C ± 0.34) than BglII (54.02°C ± 0.36). Our results clearly indicate that BGLI is structurally more rigid and stable than BglII.

Daniel Petrovič - One of the best experts on this subject based on the ideXlab platform.

  • BglII gene polymorphism of the α2β1 integrin gene is a risk factor for diabetic retinopathy in Caucasians with type 2 diabetes
    Journal of Human Genetics, 2003
    Co-Authors: Mojca Globočnik Petrovič, Marko Hawlina, Borut Peterlin, Daniel Petrovič
    Abstract:

    Platelets are thought to be involved in the pathogenesis of diabetic retinopathy. The BglII gene polymorphism of the α2β1 integrin, which is a platelet collagen receptor, has been suggested as a genetic risk factor for diabetic retinopathy in Japanese subjects. The aim of this study was to look for a relationship between the BglII gene polymorphism of the α2β1 integrin gene and the development of diabetic retinopathy in Caucasians with type 2 diabetes. Subjects with type 2 diabetes and diabetic retinopathy (n=163) were compared with diabetic subjects without diabetic retinopathy (n=95). A significantly higher frequency of the BglII (+/+) genotype of the gene polymorphism of the α2β1 integrin gene was found in patients with diabetic retinopathy compared with patients without diabetic retinopathy (19.6% vs 7.4%; P=0.008). The present study demonstrates that the BglII (+/+) genotype of the gene polymorphism of the α2β1 integrin gene is an independent risk factor (odds ratio: 2.4, 95% confidence interval 1.0–6.0; P

  • BglII gene polymorphism of the α2β1 integrin gene is a risk factor for diabetic retinopathy in caucasians with type 2 diabetes
    Journal of Human Genetics, 2003
    Co-Authors: Mojca Globočnik Petrovič, Marko Hawlina, Borut Peterlin, Daniel Petrovič
    Abstract:

    Platelets are thought to be involved in the pathogenesis of diabetic retinopathy. The BglII gene polymorphism of the α2β1 integrin, which is a platelet collagen receptor, has been suggested as a genetic risk factor for diabetic retinopathy in Japanese subjects. The aim of this study was to look for a relationship between the BglII gene polymorphism of the α2β1 integrin gene and the development of diabetic retinopathy in Caucasians with type 2 diabetes. Subjects with type 2 diabetes and diabetic retinopathy (n=163) were compared with diabetic subjects without diabetic retinopathy (n=95). A significantly higher frequency of the BglII (+/+) genotype of the gene polymorphism of the α2β1 integrin gene was found in patients with diabetic retinopathy compared with patients without diabetic retinopathy (19.6% vs 7.4%; P=0.008). The present study demonstrates that the BglII (+/+) genotype of the gene polymorphism of the α2β1 integrin gene is an independent risk factor (odds ratio: 2.4, 95% confidence interval 1.0–6.0; P<0.05) for diabetic retinopathy in Caucasians with type 2 diabetes.

Allegria Kessous - One of the best experts on this subject based on the ideXlab platform.

  • Relationship of stable integration of herpes simplex virus‐2 BglII N subfragmentXho2 to malignant transformation of human papillomavirus‐immortalized cervical keratinocytes
    International Journal of Cancer, 1998
    Co-Authors: Joseph A. Dipaolo, Craig D. Woodworth, François Coutlée, Drazen B. Zimonic, Joseph Bryant, Allegria Kessous
    Abstract:

    Transfection of the right end Xho2 subfragment of BglII N of herpes simplex virus-2 (HSV-2) into human genital keratinocytes immortalized by human papillomavirus (HPV) type 16 or 18 resulted in invasive and noninvasive indolent cystic squamous carcinomas when cells were injected into immunocompromised mice. Retention and expression of the right end portion of the BglII N fragment correlated with malignancy, as the corresponding HSV-2 sequences were integrated and transcribed in the tumorigenic cell lines. HPV-immortalized cells alone were not tumorigenic. In contrast, previous results have shown that using the entire BglII N region can malignantly transform HPV-immortalized cells, although HSV2 DNA was not retained. Together, these observations localize the transforming activity of BglII N to Xho2 and suggest that the remaining sequences have an inhibitory effect on stable integration. The Xho2 sequence is 2480 bp long and contains an open reading frame (ORF) extending from nucleotides 559 to 1797. The ORF encodes a putative protein of 412-aa with a m.w. of 42–43 kDa and is highly homologous to UL43 of HSV-1. The correlation of tumorigenicity with stable integration and expression of Xho2 DNA in HPV-immortalized cells indicates that HSV-2 should be investigated further for a possible role in cervical cancer. Int. J. Cancer 76:865–871, 1998.© 1998 Wiley-Liss, Inc.+ This article is a US Government work and, as such, is in the public domain in the United States of America.

  • relationship of stable integration of herpes simplex virus 2 BglII n subfragmentxho2 to malignant transformation of human papillomavirus immortalized cervical keratinocytes
    International Journal of Cancer, 1998
    Co-Authors: Joseph A. Dipaolo, Craig D. Woodworth, François Coutlée, Drazen B. Zimonic, Joseph Bryant, Allegria Kessous
    Abstract:

    Transfection of the right end Xho2 subfragment of BglII N of herpes simplex virus-2 (HSV-2) into human genital keratinocytes immortalized by human papillomavirus (HPV) type 16 or 18 resulted in invasive and noninvasive indolent cystic squamous carcinomas when cells were injected into immunocompromised mice. Retention and expression of the right end portion of the BglII N fragment correlated with malignancy, as the corresponding HSV-2 sequences were integrated and transcribed in the tumorigenic cell lines. HPV-immortalized cells alone were not tumorigenic. In contrast, previous results have shown that using the entire BglII N region can malignantly transform HPV-immortalized cells, although HSV2 DNA was not retained. Together, these observations localize the transforming activity of BglII N to Xho2 and suggest that the remaining sequences have an inhibitory effect on stable integration. The Xho2 sequence is 2480 bp long and contains an open reading frame (ORF) extending from nucleotides 559 to 1797. The ORF encodes a putative protein of 412-aa with a m.w. of 42–43 kDa and is highly homologous to UL43 of HSV-1. The correlation of tumorigenicity with stable integration and expression of Xho2 DNA in HPV-immortalized cells indicates that HSV-2 should be investigated further for a possible role in cervical cancer. Int. J. Cancer 76:865–871, 1998.© 1998 Wiley-Liss, Inc.+ This article is a US Government work and, as such, is in the public domain in the United States of America.

Saroj Mishra - One of the best experts on this subject based on the ideXlab platform.

  • Marginal stability drives irreversible unfolding of large multi-domain family 3 glycosylhydrolases from thermo-tolerant yeast.
    International Journal of Biological Macromolecules, 2018
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan K. Chaudhuri
    Abstract:

    Abstract Protein folding is an extremely complex and fast, yet perfectly defined process, involving interplay of many intra and inter-molecular forces. In vitro , these molecular interactions are reversible for many proteins e.g. , smaller and monomeric, organized into single domains. However, refolding of larger multi-domain/multimeric proteins is much more complicated, proceeds in a hierarchal way and is often irreversible. In a comparative study on two large, multi-domain and multimeric isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from Pichia etchellsii , we studied spontaneous and assisted refolding under three denaturing conditions viz . GdnHCl, alkaline pH and heat. During refolding, higher refolding yields were obtained for BglII in case of pH induced unfolding (13.89% ± 0.25) than BGLI (6% ± 0.85) while for GdnHCl induced unfolding, refolding was marginal (BGLI = 5% ± 0.5; BglII = 6% ± 0.69). Thermal unfolding was irreversible while assisted refolding also showed little structural gain for both proteins. When the apparent free energies of unfolding (ΔG U app ) were calculated from GdnHCl unfolding data, their values were strikingly found to be lower (BGLI ΔG U app  = 3.02 kcal/mol; BglII ΔG U app  = 2.99 kcal/mol) than reported for globular (ΔG U  = 5–15 kcal/mol)/multimeric proteins (ΔG U  = 23–29 kcal/mol) indicating marginal stability results in low refolding.

  • Structural stability and unfolding transition of β-glucosidases: a comparative investigation on isozymes from a thermo-tolerant yeast
    European Biophysics Journal, 2011
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan Kumar Chaudhuri
    Abstract:

    The folding of proteins in the milieu of the cellular environment involves various interactions among the residues of the polypeptide chain and the microenvironment where it resides. These interactions are responsible for stabilizing the protein molecule, and disruption of the same provides information about the stability of the molecule. β-Glucosidase isozymes, despite having high homology in their primary and tertiary designs, show deviations in their properties such as unfolding, refolding, and stability. In a comparative study on two large cell-wall-bound isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from a thermo-tolerant yeast, Pichia etchellsii, we have investigated guanidine hydrochloride (GdnHCl)-induced, alkali-induced, and thermal-unfolding transitions using CD and fluorescence spectroscopy and high sensitivity differential scanning calorimetry. Using spectral parameters (MRE 222 nm) to monitor the conformational transitions of the GdnHCl-induced unfolding phenomenon, it was observed that the midpoints of unfolding, apparent C _m, occurred at 1.2 M ± 0.05 and 0.8 M ± 0.03 GdnHCl, respectively, for BGLI and BglII. The alkali-induced unfolding process indicated that BGLI showed a mid-transition point at pH 11 ± 0.17, while for BglII it was at pH 10 ± 0.40, further indicating BGLI to be more stable to alkali denaturation than BglII. In the case of thermal unfolding, the midpoint of transition was observed at 63 ± 0.12°C for BGLI and at 58 ± 0.55°C for BglII. Analysis by high sensitivity differential scanning calorimeter supported the unfolding data in which BGLI showed higher melting temperature, T _m, (56.07°C ± 0.34) than BglII (54.02°C ± 0.36). Our results clearly indicate that BGLI is structurally more rigid and stable than BglII.

  • Structural stability and unfolding transition of β-glucosidases: a comparative investigation on isozymes from a thermo-tolerant yeast.
    European Biophysics Journal, 2011
    Co-Authors: Mohammad Asif Shah, Saroj Mishra, Tapan Kumar Chaudhuri
    Abstract:

    The folding of proteins in the milieu of the cellular environment involves various interactions among the residues of the polypeptide chain and the microenvironment where it resides. These interactions are responsible for stabilizing the protein molecule, and disruption of the same provides information about the stability of the molecule. β-Glucosidase isozymes, despite having high homology in their primary and tertiary designs, show deviations in their properties such as unfolding, refolding, and stability. In a comparative study on two large cell-wall-bound isozymes, β-glucosidase I (BGLI) and β-glucosidase II (BglII) from a thermo-tolerant yeast, Pichia etchellsii, we have investigated guanidine hydrochloride (GdnHCl)-induced, alkali-induced, and thermal-unfolding transitions using CD and fluorescence spectroscopy and high sensitivity differential scanning calorimetry. Using spectral parameters (MRE 222 nm) to monitor the conformational transitions of the GdnHCl-induced unfolding phenomenon, it was observed that the midpoints of unfolding, apparent C m, occurred at 1.2 M ± 0.05 and 0.8 M ± 0.03 GdnHCl, respectively, for BGLI and BglII. The alkali-induced unfolding process indicated that BGLI showed a mid-transition point at pH 11 ± 0.17, while for BglII it was at pH 10 ± 0.40, further indicating BGLI to be more stable to alkali denaturation than BglII. In the case of thermal unfolding, the midpoint of transition was observed at 63 ± 0.12°C for BGLI and at 58 ± 0.55°C for BglII. Analysis by high sensitivity differential scanning calorimeter supported the unfolding data in which BGLI showed higher melting temperature, T m, (56.07°C ± 0.34) than BglII (54.02°C ± 0.36). Our results clearly indicate that BGLI is structurally more rigid and stable than BglII.