Purification and Properties of Alcohol Acetyltransferase from Hanseniaspora valbyensis

FAN Li,XU Yan*,WANG Dong (School of Biotechnology, Southern Yangtz University, The Key Laboratory of Industrial Biotechnology, Ministry of Education, Wuxi 214036, China)

Hanseniaspora valbyensis; purification; alcohol acetyltransferase; phenethyl acetate;solid-phase microextraction

Phenethyl acetate, one of the major characteristic aroma compounds in apple wine, was synthesized by the condensation of acetyl-CoA and phenethyl alcohol under the catalysis of alcohol acetyltransferase (EC 2.3.1.84).The enzyme was dissolved from the cell membrane fraction of Hanseniaspora valbyensis, by 1% Triton and then purified by three steps of chromatographic separations: DEAE Sepharose, Sephadex G-75 and Octyl Sepharose. The purified enzyme had a single band on a SDS polyacrylamide gel, and its molecular mass was estimated to be about 37kD. The optimal temperature and pH for the purified AATase activity were 30℃ and pH7.0 respectively. It was stable between pH7.0 and pH8.0, but unstable at temperatures above 10℃. The activity was strongly inhibited by heavy metal ions such as Hg2+, Zn2+, Pb2+, but slightly stimulated by Mg2+ and slightly inhibited by EDTA and Mn2+. The enzyme catalyzes the esterification of other alcohol with acetyl-COA to form acetate ester, but shows specificity to form phenethyl acetate.