Theoretical Investigation into the Change in the Number of Water Molecules in Solvent Inaccessible Region of an Enzyme and Enzyme-substrate Complex

Abstract

Background: There may be dry enzymes, but water remains indispensable for the catalytic action of enzymes. There is not as much interest in how the presence of a drug such as aspirin and a psychoactive compound such as ethanol may affect the water-mediated role of the enzyme.
 Objectives: The objectives of this research are: 1) To assess the changes in the number of water molecules interacting with the enzyme-substrate complex and the solvent inaccessible region of a protein, 2) to determine the free energy difference due to preferential solvation and hydration, and 3) to re-examine theoretical issues in literature and relate them to the interpretation of the results.
 Methods: A major theoretical research and minor experimentation using Bernfeld method.
 Results and Discussion: The presence of ethanol/aspirin alone yielded only dehydration of the osmolyte inaccessible region and the enzyme substrate complex (ES). There was positive free energy difference (DDG) if the equilibrium constant for hydration change (Keq(1))> the equilibrium constant for folding-unfolding transition (Keq(3)); it is negative where Keq(3)> Keq(1). Analysis of various models made them valuable for the interpretation of result for feature application.
 Conclusion: The change in the number of water molecules in an osmolyte inaccessible region of the enzyme and those interacting with the ES may be either positive or negative due respectively to sucrose and ethanol/aspirin. The spontaneity of two processes, hydration and folding-unfolding transition, the free energy difference, differs. The model for water stripping, preferential interaction concept, and the KBI for osmolation and hydration can guide the interpretation of the effects of any cosolute.

The State of Proteins not with Standing, Translational Velocity is Vital for their Function

“…As stated elsewhere [21], 0.01 g of PPA was dissolved in 20 mL of distilled water to give 500 g/L while potato starch was prepared by dissolving 1 g in 90 mL of tris-HCl buffer, 5 mL of 6% (W/W) NaCl (aq.) and 5 mL of distilled water to give 1 g/100 mL.…”

“…The preparation of crude human salivary alpha amylase is as described elsewhere [23]. The determination of velocity (v) as C 3 →0 is as in previous investigation [21]. Assay for the generation of the velocities of the hydrolysis of starch is according to Bernfeld method [24]; 1 mL solution of 3, 5dihydrosalicylic acid is added to the reaction mixture to terminate the action of the enzyme at the end of the duration of assay.…”

“…However, it needs to be made clear that preferential binding of the stabilising osmolyte is largely unfavourable unlike preferential binding of destabilising osmolyte in line with the principle of solvophobicity and solvophilicity of Bolen and Baskakov [21]. In this research however, the digestive enzymes' response to the presence of a cosolute which can be described as relatively small molecules compared to the macromolecules, is investigated unlike similar issue in literature in which functionally different molecule is the case.…”

“…The substantial part of this section had been treated in a recent paper [21]. However, minor but very important issue partly based on the original idea of Bolen and Baskakov [22], needs to be examined in order to derive a useful equation of equilibrium.…”

“…It is possible too that despite this condition stated the velocity of catalytic action is lower than the velocity of the untreated native enzyme but higher than the velocity of destabiliser-treated enzyme. As in literature [21], the equations addressing the first case are given as…”