Biochemical characterization of an aspartic protease inhibitor from bacillus licheniformis: interactions with hydrolytic enzymes

Abstract

Hydrolytic enzymes (Hydrolases) are the enzymes that catalyze the hydrolysis of various chemical bonds. They are classified as EC 3 in the EC number classification of enzymes. Hydrolases can be further classified into several subclasses, based upon the bonds they act upon. Peptide hydrolases (Peptidases) are the enzymes that catalyze the peptide bonds and are recommended to be further divided into "exopeptidases" that act only near a terminus of a polypeptide chain and "endopeptidases" that act internally in polypeptide chains. The endopeptidases are divided into sub-subclasses on the basis of catalytic mechanism, and specificity is used only to identify individual enzymes within the groups. The sub-subclasses of endopeptidases are aspartic proteases (EC 3.4.23), serine proteases (EC 3.4.21), cysteine proteases (EC 3.4.22), metallo proteases (EC 3.4.24) and threonine proteases (EC 3.4.25). The aspartic proteases constitute one of the primary classes of proteolytic enzymes utilizing two aspartic acid residues in the active site for the catalytic activity with the direct participation of a water molecule. The study of the kinetic properties of this class of enzymes frequently has been motivated by their involvement in physiological and pathological processes of human, thus their effective regulators, i.e., aspartic protease inhibitors, are tremendously essential for physiological regulations. The enzymatic properties of pepsin, plasma renin, HIV1 protease, plasmepsin, lysosomal cathepsins and chymosins and their significant role in human diseases like Alzheimer’s disease, malaria, and candidal infections have evoked considerable interest for investigating the role of inhibitors.