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Imine reduction by an Ornithine cyclodeaminase/μ-crystallin homolog purified from Candida parapsilosis ATCC 7330
Date Issued
01-09-2021
Author(s)
Uma Mahesh, V. N.M.
Indian Institute of Technology, Madras
Abstract
We report a stereospecific imine reductase from Candida parapsilosis ATCC 7330 (CpIM1), a versatile biocatalyst and a rich source of highly stereospecific oxidoreductases. The recombinant gene was overexpressed in Escherichia coli and the protein CpIM1 was purified to homogeneity. This protein belongs to the Ornithine cyclodeaminase/ μ-crystallin (OCD-Mu) family of proteins which has only a few characterized members. CpIM1 catalyzed the alkylamination of α-keto acids/esters producing exclusively (S)-N-alkyl amino acids/esters e.g. N-methyl-L-alanine with > 90% conversion and > 99% enantiomeric excess (ee). The enzyme showed the highest activity for the alkylamination of pyruvate and methylamine leading to N-methyl-L-alanine with an apparent KM of 15.04 ± 2.8 mM and Vmax of 13.75 ± 1.07 μmol/min/mg. CpIM1 also catalyzed (i) the reduction of imines e.g. 2-methyl-1-pyrroline to (S)-2-methylpyrrolidine with ∼30% conversion and 75% ee and (ii) the dehydrogenation of cyclic amino acids e.g. L-Proline (as monitered by reduction of cofactor NADP+ spectrophotometrically).
Volume
31