1. D-Amino acid oxidase (D-amino acid: oxygen oxidoreductase (deaminating), EC 1.4.3.3) apoenzyme, holoenzyme and the enzyme-benzoate complex were active and stable when immobilized to aminoalkyl or carboxyalkyl agarose, or to cyanogen bromide-activated agarose. The immobilized enzyme-benzoate complex could be converted into the holo- and apoenzyme without being liberated from the agarose. 2. The apparent Michaelis constant and substrate specificity of the immobilized enzyme were similar to those of the free enzyme. The optimum pH of the reaction was shifted towards acidic side by 1.0-2.0 pH units from that of the free enzyme. 3. With increasing number of methylene groups of the 'spacer' from 3 to 5, molecular activity of the immobilized enzyme increased, while the apparent Miachaelis constant decreased.

D-Amino-Acid Oxidase↗

PubMed1977

Permeability of amino acids into liposomes.

1. A simple and rapid assay for the measurement of permeability of amino acids into liposome membrane was carried out by using the liposomes trapping D-amino acid oxidase (D-amino acid: O2 oxidoreductase (deaminating), EC 1.4.3.3) inside the membrane. 2. Permeability of amino acids into liposomes depended on the lipid composition of the membrane. Permeability of amino acids into phosphatidylcholine-cholesterol liposomes depended critically on temperature. 3. Permeability also depended on the structure of amino acids. The order of permeability was norvaline greater than isoleucine greater than leucine greater than phenylalanine greater than tryptophan greater than methionine greater than tyrosine, valine greater than threonine greater than serine greater than alanine greater than glycine.

Amino Acids↗

PubMed1976

Oxidation of sarcosine and N-alkyl derivatives of glycine by D-amino-acid oxidase.

1. Sarcosine was oxidized by D-amino-acid oxidase (D-amino-acid: O2 oxidoreductase (deaminating), EC 1.4.3.3) to yield methylamine and glyoxylic acid. A seriies of N-alkyl glycines were also oxidized by this enzyme. 2. N-Acetyl- and N-Phenylglycine inhibited the oxidase by competing with the substrate, while N-methyl-N-acetylglycine did not bind to the enzyme. This suggests the requirement of at least one unsubstituted hydrogen atom at the amino group ofglycine for binding. 3. The primary step in the reaction was the release of a proton from the substrate, indicating the formation of a substituted imino acid, which was spontaneously hydrolyzed to glyoxylic acid acid and an amine.

Animals↗

PubMed1974