Characterization of nitrile hydratase and amidase, which are responsible for the conversion of dinitriles to mononitriles, from Corynebacterium sp.

Abstract

Two enzymes, nitrile hydratase and amidase, which participate in the conversion of trans-1,4- dicyanocyclohexane (t-DCC) to frans-4-cyanocyclohexane-l-carboxylic acid (t-MCC), a tranexamic acid intermediate, were purified and characterized. Nitrile hydratase was obtained in a homogeneous state. The molecular weight of the native enzyme was 61,400 and that of the subunit 26.900, indicating a dimer structure. Valeronitrile and butyronitrile were good substrates for the enzyme. The enzyme could also hydrate benzonitrile, p-hydroxybenzonitrile and 4-cyanobenzoic acid. t-DCC was ex-clusively hydrated to fnzws-4-cyanocycIohexane-l-car boxy amide (t-MCMA), further hydration of the nitrile group of t-MCMA and t-MCC not being observed. The presence of pyrroloquinoline quinone in the enzyme was confirmed. The presence of iron was also confirmed. The amidase of the strain was also purified. The latter enzyme could hydrate t-MCMA, yielding t-MCC. The enzyme was highly resistant to SH reagents.