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Structural Biology

CRYSTALLOGRAPHY

Our principal expertise concerns protein structure determination by X-ray crystallography. In particular, we study various industrially-important enzymes, particularly of lipases and proteases. Other than their structures, we are interested in addressing their mechanism, substrate specificity and interaction, stability and kinetics. For this purpose, we employ site-directed mutagenesis, enzyme kinetics and molecular modeling in addition to X-ray crystallography in our quest to deepen our understanding on these enzymes. Using vapor-diffusion crystallization strategy, cation-π interaction at the vicinity of active site of T1 lipase was discovered for the first time among thermostable lipases. The high resolution crystal structure of T1 lipase was not only helped in the designing of mutants with improved stability and better enantioselectivity; but also designing a mini-lipase which has better kinetics properties. On the other hand, coupling the seeding technique with capillary counter diffusion crystallization has enhanced the size and diffraction quality of elastase. In efforts to improve the quality of protein crystals, crystallization under microgravity environment was performed in the International Space Station (ISS) in collaboration with Japan Aerospace Exploration Agency (JAXA). Armed with the past experiences and skills, structure of protein-substrate analogue/inhibitor complex would be our future ongoing endeavor in understanding the mechanism of action, in exploring anti-diabetic and anti-bacterial drugs.

NMR

Protein nuclear magnetic resonance (NMR) is one of the methods used in order to elucidate the structure of proteins in solution. This team focuses on the structural and functional elucidation of hypothetical proteins by NMR. At present, two small hypothetical proteins predicted to be metallo β-lactamase (a wide-spectrum antibiotics-degrading enzyme) and monothiol glutaredoxin (a possible novel protein in iron homeostasis) from Bacillus lehensis G1 as well as the copper-chaperone CsoR-like protein from Geobacillus zalihae are studied. Their possibility to act as novel drug targets as well as probes for metal detection is currently addressed.drugs.