Introduction

Biological evolution conserves protein residues that are important for structure and function. Both protein stability and function often require a certain degree of structural co-operativity between spatially neighboring residues and it has previously been shown that conserved residues occur clustered together in protein tertiary structures, enzyme active sites and protein-DNA interfaces. The analysis of sequence conservation in a protein family is a useful method for identifying residues that are functionally important for catalytic activity or binding, or responsible for providing stability to the folded structure. A typical genome contains 2-4% of genes encoding for proteolytic enzymes. 

Serine Proteases are a diverse class of enzymes, consisting of a nucleophilic Serine residue in the enzyme active site, which attacks the carbonyl moiety of the substrate peptide bond to form an acyl-enzyme intermediate. Typically, the nucleophilicity of the catalytic Ser is dependent on the catalytic triad consisting of catalytic serine stabilized by a histidine and aspartate, as well as an oxyanion hole.

Here we perform structural analysis on a set serine proteases, from the Trypsin (PA), Subtilisin (SB) and Prolyl Oligopeptidase (SC) families.