Nitrile hydratase involved in aldoxime metabolism from Rhodococcus sp. strain YH3‐3

Open Access
Publisher Website
Google Scholar
Abstract
Nitrile hydratase responsible for aldoxime metabolism from the E‐pyridine‐3‐aldoxime degrading bacterium, Rhodococcus sp. strain YH3‐3 was purified and characterized. Addition of cobalt ion was necessary for the formation of enzyme. The enzyme activity was highly induced not only by nitriles and amides but also by several aldoxime compounds. The enzyme was purified ≈ 108‐fold with a 16% yield from the cell‐free extract of the strain. The native enzyme had a Mr of ≈ 130 000 and consisted of two subunits (α‐subunit, 27 100; β‐subunit, 34 500). The enzyme contained approximately 2 mol cobalt per mol enzyme; it showed a maximum activity at 60 °C and at 40 °C under the rate assay and end‐point assay conditions, respectively, and was stable over a wide range of pH (pH 2.5–11.0). The enzyme had a wide substrate specificity: it acted on aliphatic saturated and unsaturated as well as aromatic nitriles. The N‐terminus of the β‐subunit showed good sequence similarities with those of other nitrile hydratases. Nitrile hydratase is part of the metabolic pathway for aldoximes in microorganisms.