97130-78-4Relevant articles and documents
Selective disruption of disulphide bonds lowered activation energy and improved catalytic efficiency in TALipB from Trichosporon asahii MSR54: MD simulations revealed flexible lid and extended substrate binding area in the mutant
Singh, Yogesh,Gupta, Namita,Verma, Ved Vrat,Goel, Manisha,Gupta, Rani
, p. 223 - 230 (2016)
TALipB (33 kDa) is a solvent stable, enantioselective lipase from Trichosporon asahii MSR54. It is cysteine-rich and shows activation in presence of thiol reducing agents. DIANNA server predicted three disulphide bridges C53-C195 (S1), C89-C228 (S2) and C164-C254 (S3) in the enzyme. Selective disruption of disulphide bonds by cysteine to alanine mutations at Cys53 and Cys89 of S1 and S2 bonds resulted in enzyme activation. Mutant mTALipB (S1+S2) showed increase in specific activity by ～4-fold (834 mM/mg) and improved Vmax of 6.27 μmol/ml/min at 40°Con pNP caprate. Temperature optima of mTALipB shifted from 50 to 40°C and activation energy decreased by 0.7 kcal mol-1. However, the mutant was less thermostable with a t1/2 of 18 min at 60°C as compared to t1/2 of 38 min for the native enzyme. Mutant also displayed an improved activity on all pNP esters and higher enantiomeric excess (61%) during esterification of (±) 1-phenylethanol. Far-UV CD analysis showed significant changes in secondary structure after S-S bridge disruption with 7.16% decrease in α-helices and 1.31% increase in β-sheets. In silico analysis predicted two lids (α5 and α9) in TALipB. Molecular dynamic simulations at 40°C and 50°C revealed that in the mTALipB, both the lids opened at 40°C with clockwise and anticlockwise rotations in Lid1 and Lid2, respectively. In the native protein, however, the lid was only partially open even at 50°C. Concomitant to lid flexibility, there was an extension of accessible catalytic triad surface area resulting in improved catalytic efficiency of the mutant enzyme.
The effect of the migrating group structure on enantioselectivity in lipase-catalyzed kinetic resolution?of?1-phenylethanol
Melais, Nedjma,Aribi-Zouioueche, Louisa,Riant, Olivier
, p. 971 - 977 (2016/08/08)
We have studied the effects of the acyl moiety on the enantioselectivity of three lipases: Candida antarctica B, Pseudomonas cepacia and Candida cylindracea, frequently used in kinetic resolutions by acylation or hydrolysis. The size of the acyl group was examined using various enol esters during the transesterification of 1-phenylethanol and the hydrolysis of the corresponding phenylethylesters. C. antarctica-B lipase showed the highest selectivity in the transesterification of 1-phenylethanol with isopropenyl and vinyl acetate, vinyl decanoate, vinyl laurate, (E?>?200). The esters 1-phenyl -ethyl-acetate, decanoate and laurate are also hydrolyzed with high selectivities (E?>?150) with CAL-B. The results can be correlated to the three-dimensional form of each lipase. The effect of the migrating group on the reactivity and selectivity of the lipases are discussed for both reactions.
