Stereoselectivity of the ?-lyase-catalyzed cleavage of S-cysteine conjugates of pulegone

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• 作者：Hidehiko Wakabayashi ; Motoko Wakabayashi ; Wolfgang Eisenreich and Karl-Heinz Engel
• 刊名：European Food Research and Technology
• 出版年：2002
• 出版时间：October 2002
• 年：2002
• 卷：215
• 期：4
• 页码：287-292
• 全文大小：150 KB

文摘

Stereoisomers of 8-S-cysteinyl-p-menthan-3-one synthesized from (R)- and (S)- pulegone by Michael addition of cysteine were characterized by means of GC, GC-MS, LC-MS, and 1H-NMR. Conjugates were treated with three sources of cysteine-S-conjugate #-lyase: (i) a crude enzyme extract prepared from Eubacterium limosum, (ii) tryptophanase from E. coli and (iii) yeast cells. The result was liberation of 8-mercapto-p-menthan-3-one, a powerful flavoring substance exhibiting a cassis-type odor note. The enzyme-catalyzed cleavage of the thio-ether bond proceeded with low enantioselectivity. Discrimination of diastereoisomers was more pronounced with a clear preference of the cis-configured substrates.