Abstract

SOLUBILIZATION OF KETONES IN DIMETHYLSULFOXIDE FOR USING AS ALCOHOL DEHYDROGENASE FROM SACCHAROMYCES CEREVISIAE SUBSTRATES

Ester Junko Yoriyaz and Michele Vitolo*

Abstract

Alcohol dehydrogenases (ADH) are catalysts capable of converting alcohols to ketones and vice-versa depending on the pH of the reaction medium. Each enzyme has its specificity in reference to ketones and alcohols, as well as requiring specific coenzymes (β-NAD, β-NADP, β-NADH and β-NADPH). However, the most interesting pro-chiral ketones (acetophenone, 2-hexanone, for example) to be converted into chiral alcohols (1-phenylethanol, 2-hexanol) are poorly soluble in water. In this paper, the use of dimethylsulfoxide (DMSO) mixed with water was considered for improving the solubility of the substrate and its influence on ADH from Saccharomyces cerevisiae (ADHsc). Among other results, pure acetophenone and 2-hexanone at a dilution of 1:40 and 1:20, respectively, were solubilized in a 60% (v/v) DMSO/water solution. The -NAD/-NADH recycling was also clearly observed through using a membrane reactor (MR) having ADHsc (150U) and 1mM -NADH inside it and fed alternately with acetone and 2-propanol. A similar behavior was observed operating the MR under the same conditions, but fed alternately with acetophenone and 1-phenylethanol. Thereby, the use of MR, ADHsc and - NADH for the attainment of chiral alcohols from pro-chiral ketones was adequate.

Keywords: Alcohol dehydrogenase, dimethylsulfoxide, coenzymes, prochiral-ketones.