Controlled racemization is the key component for a successful dynamic kinetic resolution (DKR), a deracemization approach that has gained significant interest to prepare optically active compounds. In this study, xerogel-immobilized W110A secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus (W110A TeSADH) is used in racemization of enantiopure phenyl-ring-containing secondary alcohols in pure organic media contra to aqueous medium required by the enzyme. The enzyme was immobilized with its cofactor nicotinamide-adenine dinucleotide phosphate (NADP+) and its reduced form, NADPH. The immobilized enzyme retained activity in organic media enabling use of sparingly water-soluble substrates. Unlike the wild-type enzyme, the extended large pocket of this mutant accommodates larger groups such as phenyl rings enabling racemization of interesting substrates such as enantiopure forms of 1-phenyl-2-propanol, 4-phenyl-2-butanol, and 1-pheny-2-butanol. The racemization reaction showed high dependency on the nature of the solvent with hexane emerging the best. A comparison with free enzyme in aqueous and biphasic media showed less notable differences. Tolerance of W110A TeSADH to organic media promises a one pot dual enzymatic dynamic kinetic resolution.

Racemization of enantiopure alcohols by a xerogel-immobilized alcohol dehydrogenase in organic solvent

248th National Meeting (2014)

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