Role of Disulfide Bonds in Stabilizing the Conformation of Selected Enzymes - An Approach Based on Divergence Entropy Applied to the Structure of Hydrophobic Core in Proteins

One of the factors responsible for tertiary structural stabilization in proteins is the presence of the hydrophobic core—a result of hydrophobic interactions within the protein body. In some proteins (especially extracellular ones) additional stabilization is provided by covalent bonds between selected Cys residues, commonly referred to as disulfide bonds. The mutual interplay of both factors and their respective contributions to stabilization are the focus of this work. The assessment of the effects of disulfide bonds isinterpreted by Fuzzy Oil Drop (FOD) model in which individual polypeptide chain fragments (including fragments which participate in SS bonds) can be evaluated in the context of their influence upon tertiary structural stabilization by comparing their corresponding theoretical and idealized hydrophobicity density distributions. The proteins were identified with both factors reinforcing each other, as well as proteins where they seem to counteract each other. The analysis presents a number of enzymes, including ribonuclease, lysozyme, disulfide isomerase and phospholipase.