Journal of Proteomics & Bioinformatics
Open Access

Abstract

Microbial Carboxylesterases: An Insight into Thermal Adaptation Using In Silico Approach

Samta Sood, Nikhil Sharma and Tek Chand Bhalla

Carboxylesterases (CE’s), are a group of esterases that catalyze the hydrolysis of carboxylic ester molecule to form alcohol and carboxylic acid in the presence of water. In silico analysis of ten carboxylesterases (E.C. 3.1.1.1) sequences from mesophilic and thermophilic organisms for various physiochemical parameters and amino acid comparison has been done. Ten sequences, five from each group were retrieved from NCBI and were aligned using multiple sequence alignment tool MUSCLE. The phylogenetic relationship between the two groups has been found using maximum parsimony method of MEGA-6. These sequences were further analyzed using online ProtParam ExPASy tool for some important physicochemical properties. Multiple sequence alignment (MSA) showed the presence of conserved catalytic triad S157, D254, H284. Maximum parsimony method using MEGA-6 distinguished the mesophilic and thermophilic esterases into their respected subgroups. The two groups showed significant variation in their physical and chemical properties. Theoretical pI and negatively charged residues were found to be significant in the present study. Amino acid Gln (Q), Val (V) showed significant statistical variation with 1.7 and 1.5 fold. Fold value statistics showed dominance of Asn (1.4), Gln (1.7), Cys (1.4), Thr (1.3), Trp (1.4) and Lys (1.2) in mesophiles whereas, Ala (1.1), Arg (1.5), Ileu (1.3), Glu (1.2), Tyr (1.2), Val (1.5) in thermophiles. Polar amino acid residues Gln (Q), Asn (N), Cys (C) Lys (K), Thr (T) and Glu (D) beside to their dominance in one and in other group help to distinguish lipases from esterases for their affinity for water soluble short chain fatty esters. Because of affinity of these amino acids to water molecules, they have tendency to be on the exterior of a protein thus can interact with polar region of surfaces.