Alston, M.J. and Freedman, R.B. (2002) A comparison of lipase-catalysed ester and lactone synthesis in low-water systems: analysis of optimum water activity. Biotechnology and Bioengineering, 77 (6). pp. 641-650. ISSN 0006-3592.
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We investigated the effects of the lyophilisation medium (enzyme plus buffer salt and additives) and of water activity (a(w)) on the catalytic properties of lipase from Chromobacterium viscosum (lipase CV) in organic solvents; catalysis of ester and lactone synthesis were compared and, despite the similarities of the reactive groups involved in these reactions, some interesting differences were observed. Including 2-[N-morpholino]ethanesulfonic acid (MES) buffer in the lyophilisation medium of lipase CV increased its catalytic activity in transesterification and lactonisation, although the buffer salt requirement for maximal activity differed between the two reactions. Sorbitol, glucose, lactose, 18-crown-6 (crown ether 18-C-6), beta-cyclodextrin and bovine serum albumin were employed as alternative additives in the transesterification reaction, but were not as effective as MES buffer. Salt hydrates were used to investigate the effect of a(w) on esterification and lactonisation reactions catalysed by lipase CV. The maximum rate of hexadecanolide synthesis in toluene occurred at a(w) = 0.48. The optimum a(w) for the transesterification reaction in heptane/alcohol mixtures depended on the alcohol substrate employed (1-heptanol, 2-heptanol, or 3-methyl-3-hexanol) but not on the acyl donor (p-NP acetate or caprylate). The optimum a(w) values for both reactions were unchanged when a common solvent system (toluene/1-heptanol) was employed, indicating that the dependence of enzyme activity on a(w) is an intrinsic property of the enzyme-catalysed reaction and not a function of the solvent or other additives.
|Additional information:||0006-3592 (Print) Comparative Study Journal Article Research Support, Non-U.S. Gov't|
|Uncontrolled keywords:||Biotechnology Buffers Catalysis Chromobacterium/enzymology Esters/*chemical synthesis Kinetics Lactones/*chemical synthesis Lipase/*metabolism Water/*chemistry|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Biosciences > Protein Science Group|
|Depositing User:||Sue Davies|
|Date Deposited:||09 Sep 2008 18:26|
|Last Modified:||14 Jan 2010 14:25|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/6727 (The current URI for this page, for reference purposes)|
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