Geometric Simulation Approach for Grading and Assessing the Thermostability of CALBs.

B Senthilkumar,D Meshachpaul,R Rajasekaran

doi:10.1155/2016/4101059

B Senthilkumar, D Meshachpaul + Show 1 more

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https://doi.org/10.1155/2016/4101059

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Abstract

Candida antarctica lipase B (CALB) is a known stable and highly active enzyme used widely in biodiesel synthesis. In this work, the stability of native (4K6G) and mutant (4K5Q) CALB was studied through various structural parameters using conformational sampling approach. The contours of polar surface area and surface area of mutant CALB were 11357.67 Å2 and 30007.4 Å2, respectively, showing an enhanced stability compared to native CALB with a statistically significant P value of < 0.0001. Moreover, simulated thermal denaturation of CALB, a process involving dilution of hydrogen bond, significantly shielded against different intervals of energy application in mutant CALB revealing its augmentation of structural rigidity against native CALB. Finally, computational docking analysis showed an increase in the binding affinity of CALB and its substrate (triglyceride) in mutant CALB with Atomic Contact Energy (ACE) of −91.23 kcal/mol compared to native CALB (ACE of −70.3 kcal/mol). The computational observations proposed that the use of mutant CALB (4K5Q) could serve as a best template for production of biodiesel in the future. Additionally, it can also be used as a template to identify efficient thermostable lipases through further mutations.

Highlights

Lipases (EC 3.1.1.3, triacylglycerol lipase) exist as proficient catalysts of high demand in varied fields
Cluster analysis was carried out using conformation sampling method in which polar surface area (PSA) and surface area (SA) of mutant Candida antarctica lipase B (CALB) showed their significance in solvent accessibility, thereby defining functional activity of CALB
Hydrogen bond dilution showed lack of stable hydrogen bonds in native CALB beyond energy level of −7 kcal/mol, whereas mutant CALB showed a presence of 22 bonds to be thermally denatured at a supply of more than −7 kcal/mol of energy

Summary

Introduction

Lipases (EC 3.1.1.3, triacylglycerol lipase) exist as proficient catalysts of high demand in varied fields. CALB is a serine hydrolase, consisting of SerHis-Asp catalytic triad with serine acting as a nucleophile [5] It is well known in industrial field for its chemical property involving the hydrolysis of triacylglycerols into fatty acids, diacylglycerol, monoacylglycerol, and glycerol [6]. It is characterized for its stereoselectivity, thermal stability, and activity, making it a common choice of enzyme for organic synthesis reactions and a competent biocatalyst for industrial applications.

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