Purification and Characterization of Maleylacetate Reductase from Nocardioides simplex 3E Utilizing Phenoxyalcanoic Herbicides 2,4-D and 2,4,5-T

V. M. Travkin, E. V. Linko, and L. A. Golovleva^*

Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (095) 923-3602; E-mail: Golovleva@ibpm.Serpukhov.su

^* To whom correspondence should be addressed.

Received July 1, 1998; Revision received January 21, 1999

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Maleylacetate reductase was isolated and purified from the Gram-positive strain Nocardioides simplex 3E which is able to utilize the phenoxyalcanoic herbicides 2,4-D and 2,4,5-T. Cells were grown on 2,4-D as the sole carbon source. The enzyme was purified by 380-fold with 3.0% yield. The purified maleylacetate reductase is a homodimer with subunit molecular mass of 37 kD. The enzyme required NADH as a cofactor; the K_m for maleylacetate is 25 µM; V_max (with NADH as cofactor) and k_cat are 185 U/mg and 6845 min^-1, respectively. The enzyme is very unstable; its pH and temperature optima are at 7.0-7.1 and 50°C, respectively.

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KEY WORDS: maleylacetate reductase, Nocardioides simplex 3E, phenoxyalcanoic herbicides, 2,4-D

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