[218c] l-Amino acid oxidase (rat kidney). Metabolism of Amino Acids and Amines Part B. Elsevier; 1971. pp. 601-5. [DOI: 10.1016/0076-6879(71)17106-6]

Structure of peptidoglycan from Thermus thermophilus HB8

The composition and structure of peptidoglycan (murein) extracted from the extreme thermophilic eubacterium Thermus thermophilus HB8 are presented. The structure of 29 muropeptides, accounting for more than 85% of total murein, is reported. The basic monomeric subunit consists of N-acetylglucosamine-N-acetylmuramic acid-L-Ala-D-Glu-L-Orn-D-Ala-D-Ala, acylated at the delta-NH2 group of Orn by a Gly-Gly dipeptide. In a significant proportion (about 23%) of total muropeptides, the N-terminal Gly is substituted by a residue of phenylacetic acid. This is the first time phenylacetic acid is described as a component of bacterial murein. Possible implications for murein physiology and biosynthesis are discussed. Murein cross-linking is mediated by D-Ala-Gly-Gly peptide cross-bridges. Glycan chains are apparently terminated by (1-->6) anhydro N-acetylmuramic acid residues. Neither reducing sugars nor murein-bound macromolecules were detected. Murein from T. thermophilus presents an intermediate complexity between those of gram-positive and gram-negative organisms. The murein composition and peptide cross-bridges of T. thermophilus are typical for a gram-positive bacterium. However, the murein content, degree of cross-linkage, and glycan chain length for T. thermophilus are closer to those for gram-negative organisms and could explain the gram-negative character of Thermus spp.

A novel L-glutamate oxidase from Streptomyces endus. Purification and properties

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 Km value for L-glutamic acid in air-saturated phosphate pH 7.0 was estimated to be 1.1 mM, the Km for oxygen was calculated to be 1.86 mM at saturating concentration of L-glutamic acid. The enzymic reaction is inhibited by Ag+ and Hg2+ 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.