%0 Journal Article
%T Optimising biocatalyst design for obtaining high transesterification activity by ¦Á-chymotrypsin in non-aqueous media
%A Kusum Solanki
%A Munishwar Gupta
%J Chemistry Central Journal
%D 2008
%I BioMed Central
%R 10.1186/1752-153x-2-2
%X It was found that EPRPs of ¦Á-chymotrypsin prepared by precipitation with n-propanol in the presence of trehalose contained substantial amount of trehalose (even though trehalose alone at these lower concentrations was not precipitated by n-propanol). The presence of trehalose in these EPRPs resulted in much higher transesterification rates (45.2 nmoles mg-1min-1) as compared with EPRPs prepared in the absence of trehalose (16.6 nmoles mg-1min-1) in octane. Both kinds of EPRPs gave similar initial transesterification rates in acetonitrile. Use of higher concentrations of trehalose (when trehalose alone also precipitates out), resulted in the formation of PCMCs, which showed higher transesterification rates in both octane and acetonitrile. SEM analysis showed the relative sizes of various preparations. Presence of trehalose resulted in EPRPs of smaller sizes.The two different forms of enzymes (EPRP and PCMC) known to show higher activity in organic solvents were found to be different only in the way the low molecular weight additive was present along with the protein. Therefore, the enhancement in the transesterification activity in EPRPs prepared in the presence of trehalose was due to: (a) better retention of essential water layer for catalysis due to the presence of the sugar. This effect disappeared where the reaction media was polar as the polar solvent (acetonitrile) is more effective in stripping off the water from the enzyme; (b) reduction in particle size as revealed by SEM. In the case of PCMC, the enhancement in the initial rates was due to an increase in the surface area of the biocatalyst since protein is coated over the core material (trehalose or salt).It is hoped that the insight gained in this work would help in a better understanding for designing high activity biocatalyst preparation of non-aqueous media.The possibility of using enzymes in low water containing organic solvents has expanded their applications in organic synthesis [1-4]. In many cases
%U http://journal.chemistrycentral.com/content/2/1/2