|YU, YING - Emory University
|LUTZ, STEFAN - Emory University
|Compton, David - Dave
Submitted to: Journal of Molecular Catalysis B: Enzymatic
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2011
Publication Date: 8/25/2011
Citation: Laszlo, J.A., Yu, Y., Lutz, S., Compton, D.L. 2011. Glycerol acyl-transfer kinetics of a circular permutated Candida antarctica Lipase B. Journal of Molecular Catalysis B: Enzymatic. 72:175-180. DOI: 10.1016/j.molcatb.2011.06.002.
Interpretive Summary: Domestic and international markets for oils may be increased by our findings that a modified enzyme works better than the original for forming novel, high-value vegetable oil products for skin care applications. Finding new uses for commodity vegetable oils can raise the income of oilseed producers. Vegetable oils can be altered by enzymes to introduce into the oils functional properties, such as high antioxidant capacity, that promote their inclusion in skin lotions and creams. To make these changes to the oil, sometimes the enzyme itself needs to be modified first so that it will conduct the required reaction. The present work describes how a microbial enzyme with a single change to its structure allows it to more quickly incorporate unique fatty acids into products. A potential drawback was the unexpected finding that this new enzyme is more readily inhibited by a component of vegetable oils, which makes the enzyme work more slowly. The enzyme may need further modifications to fully exploit its potential. The new information in this work will help scientists seeking beneficial changes to the enzyme to enable the synthesis of novel products from vegetable oils.
Technical Abstract: Triacylglycerols containing a high abundance of unusual fatty acids, such as y-linolenic acid, or novel arylaliphatic acids, such as ferulic acid, are useful in pharmaceutical and cosmeceutical applications. Candida antarctica lipase B (CALB) is quite often used for non-aqueous synthesis, although the wild-type enzyme can be rather slow with bulky and sterically hindered acyl donor substrates. The catalytic performance of a circularly permutated variant of CALB, cp283, with various acyl donors and glycerol was examined. In comparison to wild-type CALB, butyl oleate and ethyl y-linolenate glycerolysis rates were 2.2- and 4.0-fold greater, respectively. Cp283 showed substrate inhibition by glycerol, which was not the case with the wild-type version. With either ethyl ferulate or vinyl ferulate acyl donors, cp283 matched the performance of wild-type CALB. Changes in active site accessibility resulting from circular permutation led to increased catalytic rates for bulky fatty acid esters but did not overcome the steric hindrance or energetic limitations experienced by arylaliphatic esters.