This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Misono, H Articles by Nagasaki, S Search for Related Content PubMed PubMed Citation Articles by Misono, H Articles by Nagasaki, S

research-article

Purification and characterization of a dimeric phenylalanine dehydrogenase from Rhodococcus maris K-18.

Department of Agricultural Chemistry, Kochi University, Japan.

ABSTRACT

NAD+-dependent phenylalanine dehydrogenase (EC 1.4.1.) was purified to homogeneity from a crude extract of Rhodococcus maris K-18 isolated from soil. The enzyme had a molecular mass of about 70,000 daltons and consisted of two identical subunits. The enzyme catalyzed the oxidative deamination of L-phenylalanine and several other L-amino acids and the reductive amination of phenylpyruvate and p-hydroxyphenylpyruvate. The enzyme required NAD+ as a natural coenzyme. The NAD+ analog 3-acetylpyridine-NAD+ showed much greater coenzyme activity than did NAD+. D-Phenylalanine, D-tyrosine, and phenylethylamine inhibited the oxidative deamination of L-phenylalanine. The enzyme reaction was inhibited by p-chloromercuribenzoate and HgCl2. Initial-velocity and product inhibition studies showed that the reductive amination proceeded through a sequential ordered ternary-binary mechanism. NADH bound first to the enzyme, followed by phenylpyruvate and then ammonia, and the products were released in the order L-phenylalanine and NAD+. The Michaelis constants were as follows: L-phenylalanine, 3.8 mM; NAD+, 0.25 mM; NADH, 43 microM; phenylpyruvate, 0.50 mM; and ammonia, 70 mM.

This article has been cited by other articles:

• Pidoux, O., Argenson, J.-N., Jacomo, V., Drancourt, M. (2001). Molecular Identification of a Dietzia maris Hip Prosthesis Infection Isolate. J. Clin. Microbiol. 39: 2634-2636 [Abstract] [Full Text]