Effects of stabilizing additives on the activity of alpha-chymotrypsin in organic solvent

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• 作者：Francesco Secundo ; Gabriel L. Barletta ; Gloria Parini ; Gabriella Roda
• 关键词：Biocatalysis ; Lyoprotectants ; Protein stability ; Protein cross-linking
• 刊名：Journal of Molecular Catalysis B: Enzymatic
• 出版年：2012
• 出版时间：December, 2012
• 年：2012
• 卷：84
• 期：Complete
• 页码：128-131
• 全文大小：396 K

文摘

The ability of ectoin, hydroxyectoin, glycoin (known as extremolytes), glutaraldehyde (GA) and methoxypoly(ethylene glycol) (MeOPEG) to produce formulations of alpha-chymotrypsin (¦Á-CT) more active than the native enzyme in organic solvents, was tested. The activity in toluene of lyophilized ¦Á-CT when ectoin, MeOPEG (1:1, w/w) or GA (0.1 % , w/v) were used was 10-, 46-, and 260-fold higher than in the absence of additives, respectively; furthermore, when using MeOPEG and GA together the activity increased 370-fold. GA increased the activity of ¦Á-CT in organic solvent, in spite of its inactivating effect in water. The activating effect of GA was dependent on the water activity (a_w) at which ¦Á-CT + GA was equilibrated and on the reaction system. At a_w 0.06 it was observed at all GA concentrations employed (0.025-0.25 % , w/v, in the enzyme water solution before lyophilization), whereas at a_w 0.96 it was found only at 0.025 % GA. Infrared spectroscopic data indicated that prolonged exposure of ¦Á-CT films to GA in buffer causes changes to the enzyme secondary structure, favoring the hydration of the enzyme, which ultimately suggests a higher accessibility of the substrates to the enzyme.