Open AccessA novel l ‐glutamate oxidase from Streptomyces endus
Author(s) -
BÖHMER Annette,
MÜLLER Anita,
PASSARGE Margit,
LIEBS Peter,
HONECK Horst,
MÜLLER HansGeorg
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb14834.x
Subject(s) - chemistry , glutamic acid , hydrogen peroxide , isoelectric point , molecular mass , chromatography , aspartic acid , polyacrylamide gel electrophoresis , oxidase test , asparagine , gel electrophoresis , enzyme , amino acid , biochemistry
A new flavoenzyme using molecular oxygen to oxidize l ‐glutamic acid has been purified to homogeneity, as judged by polyacrylamide gel electrophoresis, from the culture medium of Streptomyces endus . Hydrogen peroxide, 2‐oxoglutaric acid and ammonia are formed as products. Among 25 amino acids tested including d ‐glutamic acid, l ‐glutamine and l ‐aspartic acid, only l ‐glutamic acid is converted. The molecular mass of the enzyme was estimated to be about 90 kDa by gel chromatography and 50 kDa by SDS/PAGE. The subunit contains 1 molecule noncovalently bound FAD. The absorption spectrum shows maxima at 273, 355 and 457 nm and the isoelectric point is at pH 6.2. The K m value for l ‐glutamic acid in air‐saturated phosphate pH 7.0 was estimated to be 1.1 mM, the K m for oxygen was calculated to be 1.86 mM at saturating concentration of l ‐glutamic acid. The enzymic reaction is inhibited by Ag + and Hg 2+ ions. The enzyme described here distinctly differs from two microbial l ‐glutamate oxidases purified hitherto, with regard to extremely high substrate specificity and to the subunit structure.