Characterization of enzymes specifically producing chiral flavor compounds (R)- and (S)-1-phenylethanol from tea (Camellia sinensis) flowers

Publication date: Available online 16 December 2018Source: Food ChemistryAuthor(s): Ying Zhou, Qiyuan Peng, Ling Zhang, Sihua Cheng, Lanting Zeng, Fang Dong, Ziyin YangAbstract1-Phenylethanol is a chiral flavor compound that has enantiomers, (R)- and (S)-1-phenylethanol, with different flavor properties. Given that isolating these enantiomers from plants is low yielding and costly, enzymatic synthesis presents an alternative approach. However, the genes/enzymes that specifically produce (R)- and (S)-1-phenylethanol in plants are unknown. To identify these enzymes in tea (Camellia sinensis) flowers, 21 short chain dehydrogenase (SDR) genes were isolated from tea flowers, cloned, and functionally characterized. Several recombinant SDRs in Escherichia coli exhibited activity for converting acetophenone to (S)-1-phenylethanol (CsSPESs,>99.0%), while only one SDR produced (R)-1-phenylethanol (CsRPES, 98.6%). A pair of homologue enzymes (CsSPES and CsRPES) showed a strong preference for NADPH cofactor, with optimal enzymatic reaction conditions of 45–55 °C and pH 8.0. Identification of the tea flower-derived gene responsible for specific synthesis of (R)- and (S)-1-phenylethanolsuggests enzymatic synthesis of enantiopure 1-phenylethanol is possible using a plant-derived gene.
Source: Food Chemistry - Category: Food Science Source Type: research