Baker's yeast activity in an organic solvent system

The baker's yeast mediated reduction of ethyl 3-oxobutanoate-3-C-13 in hexane was conducted in an NMR tube at 20 degreesC and a C-13 NMR spectrum recorded each hour. A plot of relative peak intensity against time allowed the progress of the reaction to be monitored. A series of reactions was carried out in which the yeast was pretreated with the organic solvent system for 3, 6, 12 and 24 h prior to the addition of the substrate. From the initial rate of these reactions it was determined that in hexane the enzyme activity remained constant for about 12 h and then rapidly decreased until after 24 h very Little activity remained. The reaction was also carried out at 10 degreesC and 30 degreesC. At the lower temperature, the reaction was slower but enzyme activity was maintained for more than 60 h, while at 30 degreesC the enzyme activity had ceased after 8 h. (C) 2001 Elsevier Science B.V. All rights reserved.