Insilico Studies and Homology Modeling of A Mesophilic Mojavensis Keratinase

Background and aim: keratinase is one of the proteolytic enzymes in nature. this enzyme recently named as a serine protease because 97 percent of its sequence was similar to the alkaline protease that inhibited by serine protease inhibitors. using bioinformatics methods to predict protein structure is cost-effective, efficient and fast because the process of crystallography is very time-consuming and costly. methods: in this study, primary structure analysis and evaluation of the secondary structure of the keratinase enzyme of bacillus mojavensis (ay665611.1) were predicted and calculated by the online software protparam and phyre2, respectively. keratinase mojavensis binding sites were identified using the cofactor server. the conserved sequence was displayed using the jalview software. homology modeling with pdb-blast was performed by modeller software and its results were evaluated in procheck, saves, prosa and rampage. results: theoretical biochemical properties showed that keratinase mojavensis was a 38.86 kda subtilisin serine protease with an isoelectric point of 8.73, instability index 12.83, gravy -0.039 and aliphatic coefficient of 83.93, which made it a highly stable protein. the secondary structure of keratinase mojavensis is composed of 27% ?-helix, 26% ?-sheet. predicting the 3d structure showed that the predicted model had z-score -7.34 and the verify-3d index higher than 2. the results of ramachandran graph showed that 90.4% of amino acids were in the favored regions, 6.2% in allowed regions, and 3.4% in outlier regions. examination and analysis of the phylogenetic tree of bacillus mojavensis showed that this bacillus is a peptidase that belongs to the subtilisin serine protease group. pdb-blast results showed that keratinase mojavensis had the highest structural similarity to 4gi3a structure. homology modeling was based on the crystallographic structure of 4gi3a, which is a subtilisin. according to the results of the cofactor server, aspartate 137, histidine 168, asparagine 259 and serine 325 amino acids are in the active site of the enzyme. the molecular function results showed that this enzyme is a serine-type with endopeptidase activity. conclusion: predicting and determining the theoretical biochemical properties of the enzymes could aid in protein engineering studies to enhance protein stability, study of proteins against inhibitors by docking, and molecular dynamics simulations.