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Facile modulation of enantioselectivity of thermophilic Geobacillus zalihae lipase by regulating hydrophobicity of its Q114 oxyanion


Citation

Abdul Wahab, Roswanira and Basri, Mahiran and Raja Abdul Rahman, Raja Noor Zaliha and Salleh, Abu Bakar and Abdul Rahman, Mohd Basyaruddin and Leow, Adam Thean Chor (2016) Facile modulation of enantioselectivity of thermophilic Geobacillus zalihae lipase by regulating hydrophobicity of its Q114 oxyanion. Enzyme and Microbial Technology, 93-94. pp. 174-181. ISSN 0141-0229; ESSN: 1879-0909

Abstract / Synopsis

Site-directed mutagenesis of the oxyanion-containing amino acid Q114 in the recombinant thermophilic T1 lipase previously isolated from Geobacillus zalihae was performed to elucidate its role in the enzyme⿿s enantioselectivity and reactivity. Substitution of Q114 with a hydrophobic methionine to yield mutant Q114M increased enantioselectivity (3.2-fold) and marginally improved reactivity (1.4-fold) of the lipase in catalysing esterification of ibuprofen with oleyl alcohol. The improved catalytic efficiency of Q114L was concomitant with reduced flexibility in the active site while the decreased enantioselectivity of Q114L could be directly attributed to diminished electrostatic repulsion of the substrate carboxylate ion that rendered partial loss in steric hindrance and thus enantioselectivity. The highest E-values for both Q114L (E-value 14.6) and Q114M (E-value 48.5) mutant lipases were attained at 50 °C, after 12⿿16 h, with a molar ratio of oleyl alcohol to ibuprofen of 1.5:1 and at 2.0% (w/v) enzyme load without addition of molecular sieves. Pertinently, site-directed mutagenesis on the Q114 oxyanion of T1 resulted in improved enantioselectivity and such approach may be applicable to other lipases of the same family. We demonstrated that electrostatic repulsion phenomena could affect flexibility/rigidity of the enzyme-substrate complex, aspects vital for enzyme activity and enantioselectivity of T1.


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Additional Metadata

Item Type: Article
Subject: T1 lipase; Geobacillus zalihae; 2DSN; Site-directed mutagenesis; Enantioselectivity; Oxyanion
Divisions: Faculty of Biotechnology and Biomolecular Sciences
Faculty of Science
Institute of Bioscience
DOI Number: https://doi.org/10.1016/j.enzmictec.2016.08.020
Publisher: Elsevier
Depositing User: Nurul Ainie Mokhtar
Date Deposited: 09 Mar 2018 11:09
Last Modified: 09 Mar 2018 11:09
Altmetrics: http://www.altmetric.com/details.php?domain=psasir.upm.edu.my&doi=10.1016/j.enzmictec.2016.08.020
URI: http://psasir.upm.edu.my/id/eprint/54264
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