Chiral resolution function with immobilized food proteins.

Abstract

We confirmed that an NAD(P)+-dependent secondary alcohol dehydrogenase (NAD(P)-E) can be easily and effectively isolated from pea, soybean, and wheat proteins immobilized with calcium alginate gel (IPP, ISP, and IWP, respectively). The estimated molecular mass of NAD(P)-E is 138.7 kDa, and the concentrations of NAD(P)-E in solution are 36.2 (IPP), 53.9 (ISP), and 93.7 (IWP) microg/mL. The NAD(P)-E oxidizes only (R)-isomers highly enantioselectively; thus, greater than 99% ee(s) of (S)-isomers can be obtained from corresponding rac-aryl methyl carbinols (1, 2a-6a, and 2b-7b). The amount of food protein needed for 1 g of substrate (B/S ratio) is approximately 20. Thus, in comparison to current biocatalysts, certain food proteins can serve as asymmetric reagent bases, providing easily obtained, low-cost natural catalysts with stereoselectivity, regioselectivity, and substrate specificity that work under mild conditions for asymmetric synthesis of organic compounds. Moreover, this "fourth" function of food may help build a sustainable society by synthesizing optically active secondary alcohols in an environmentally friendly manner.