pH-Dependent Protein Conformational Changes in Albumin:Gold Nanoparticle Bioconjugates:  A Spectroscopic Study

Langmuir ◽  
2007 ◽  
Vol 23 (5) ◽  
pp. 2714-2721 ◽  
Author(s):  
Li Shang ◽  
Yizhe Wang ◽  
Junguang Jiang ◽  
Shaojun Dong
Keyword(s):  
Spectroscopic Study ◽  
Conformational Changes ◽  
Protein Conformational Changes ◽  
Dependent Protein ◽  
Ph Dependent

Temperature- and pH-dependent protein conformational changes investigated by terahertz dielectric spectroscopy

2019 ◽  
Vol 98 ◽  
pp. 260-265 ◽  
Author(s):  
Ziyi Zang ◽  
Shihan Yan ◽  
Xiaohui Han ◽  
Dongshan Wei ◽  
Hong-Liang Cui ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Dielectric Spectroscopy ◽  
Protein Conformational Changes ◽  
Dependent Protein ◽  
Ph Dependent

Na+/H+ exchanger: proton modifier site regulation of activity

1998 ◽  
Vol 76 (5) ◽  
pp. 743-749 ◽  
Author(s):  
James L Kinsella ◽  
Phillip Heller ◽  
Jeffrey P Froehlich
Keyword(s):  
Conformational Changes ◽  
Molecular Mechanisms ◽  
Transition Rates ◽  
Extrinsic Factors ◽  
Pharmacological Agents ◽  
Protein Conformational Changes ◽  
Regulation Of Activity ◽  
Ph Dependent ◽  
Second Messenger Pathways ◽  
Exchange Activity

The Na+/H+ exchangers (NHE1-6) are integral plasma membrane proteins that catalyze the exchange of extracellular Na+ for intracellular H+. In addition to Na+ and H+ transport sites, NHE has an intracellular allosteric H+ modifier site that increases exchange activity when occupied by H+. NHE activity is also subject to control by a variety of extrinsic factors including hormones, growth factors, cytokines, and pharmacological agents. Many of these factors, working through second messenger pathways acting directly or indirectly on NHE, regulate NHE activity by shifting the apparent affinity of the H+ modifier site to more alkaline or more acid pH. The underlying molecular mechanisms involved in the activation of NHE by the H+ modifier site are poorly understood at this time, but likely involve slow protein conformational changes within a NHE oligomer. In this paper, we present initial experiments measuring intracellular pH-dependent transition rates between active and inactive oligomeric conformations and describe how these transition rates may be important for overall regulation of NHE activity.Key words: Na+/H+ exchangers, oligomers, hysteresis.

scholarly journals Interactions of urdine diphosphate glucose dehydrogenase with the inhibitor urdine diphosphate xylose

1975 ◽  
Vol 145 (2) ◽  
pp. 129-134 ◽  
Author(s):  
P A Gainey ◽  
C F Phelps
Keyword(s):  
Conformational Changes ◽  
Protein Concentration ◽  
Protein Modification ◽  
Fluorescence Enhancement ◽  
Glucose Dehydrogenase ◽  
Protein Fluorescence ◽  
Low Protein ◽  
Protein Conformational Changes ◽  
Diphosphate Glucose ◽  
Ph Dependent

1. UDP-xylose and UDP-glucose both bind to UDP-glucose dehydrogenase in the absence of NAD+, causing an enhancement of protein fluorescence. 2. The binding of UDP-xylose is pH-dependent, tighter binding being observed at pH8.2 than at pH8.7. 3. At low protein concentrations sigmiodal profiles of fluorescence enhancement are obtained on titration of the enzyme with UDP-xylose. As the protein concentration is increased the titration profiles become progressively more hypebolic in shape. 4. The markedly different titration profiles obtained on titrating enzyme and the enzyme-NAD+ complex with UDP-xylose suggests a conformational difference between these two species 5. NAD+ lowere the apparent affinity of the enzyme for UDP-xylose. 6. There is no change in the apparent moleculare weight of UDP-glucose dehydrogenase on binging UDP-xylose. 7. Protein modification by either diethyl pyrocarbonate or 5, 5′-dithiobis-(2-nitrobenzoate) does not “desensitize” the enzyme with respect to the inhibition by UDP-xylose. 8. UDP-xylose lowers the affinity of the enzyme for NADG. 9. It is suggested that UDP-xylose is acting as a substrate analogue of UDP-glucose and causes protein-conformational changes on binding to the enzyme.

pH-Dependent Thermal Stability of Vibrio cholerae L-asparaginase

2019 ◽  
Vol 26 (10) ◽  
pp. 743-750 ◽  
Author(s):  
Remya Radha ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Vibrio Cholerae ◽  
Conformational Changes ◽  
Kinetic Studies ◽  
Structural Features ◽  
Structure Stability ◽  
Kcal Mole ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Ph Dependent ◽  
Ph Range

Background:pH is one of the decisive macromolecular properties of proteins that significantly affects enzyme structure, stability and reaction rate. Change in pH may protonate or deprotonate the side group of aminoacid residues in the protein, thereby resulting in changes in chemical and structural features. Hence studies on the kinetics of enzyme deactivation by pH are important for assessing the bio-functionality of industrial enzymes. L-asparaginase is one such important enzyme that has potent applications in cancer therapy and food industry.Objective:The objective of the study is to understand and analyze the influence of pH on deactivation and stability of Vibrio cholerae L-asparaginase.Methods:Kinetic studies were conducted to analyze the effect of pH on stability and deactivation of Vibrio cholerae L-asparaginase. Circular Dichroism (CD) and Differential Scanning Calorimetry (DSC) studies have been carried out to understand the pH-dependent conformational changes in the secondary structure of V. cholerae L-asparaginase.Results:The enzyme was found to be least stable at extreme acidic conditions (pH< 4.5) and exhibited a gradual increase in melting temperature from 40 to 81 °C within pH range of 4.0 to 7.0. Thermodynamic properties of protein were estimated and at pH 7.0 the protein exhibited ΔG37of 26.31 kcal mole-1, ΔH of 204.27 kcal mole-1 and ΔS of 574.06 cal mole-1 K-1.Conclusion:The stability and thermodynamic analysis revealed that V. cholerae L-asparaginase was highly stable over a wide range of pH, with the highest stability in the pH range of 5.0–7.0.

scholarly journals Protein conformational changes and myelin solubilization by anion-detergent solutions

FEBS Letters ◽  
1992 ◽  
Vol 309 (3) ◽  
pp. 376-380 ◽  
Author(s):  
Jaime Monreal ◽  
Pedro Carmona ◽  
Pilar Regueiro ◽  
Ricardo S. Diaz
Keyword(s):  
Conformational Changes ◽  
Protein Conformational Changes ◽  
Detergent Solutions
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