Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.3 (ascorbate oxidase)
 778 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distributions of D-amino acid oxidase (D-AAO, EC 1.4.3.3) and D-aspartate oxidase (D-AspO, EC 1.4.3.1) activities were examined on several tissues of various fish species. Both enzyme activities were commonly high in kidney and liver and low in intestine with some exceptions. After oral administration of D-alanine at 5 micromol /g body weight(-1)day(-1) to carp for 30 days, D-AAO activity increased by about 8-, 3-, and 1.5-fold in intestine, hepatopancreas, and kidney, respectively, whereas no increase was found in brain. In contrast, oral administration of D-glutamate or D-aspartate did not show any increase of D-AspO activity in any tissues. D-AAO and D-AspO of common carp kidney and hepatopancreas were subcellularly localized in peroxisomes, as clarified in mammals. D-proline was the best substrate for D-AAO in rainbow trout kidney, common carp kidney, and hepatopancreas, followed by D-alanine and D-phenylalanine. N-methyl-D-aspartate was the best substrate for D-AspO in rainbow trout kidney and common carp hepatopancreas. The optimal pH for D-AAO in rainbow trout kidney was broad, from 7.4 to 8.2, and that for D-AspO was around 10. D-AAO was inhibited by benzoate known as D-AAO inhibitor and D-AspO was strongly inhibited by meso-tartarate as D-AspO inhibitor. From these results, at least D-AAO in fish is considered to work as a metabolizing agent of exogenous and endogenous free D-alanine that is abundant in aquatic invertebrates such as crustaceans and bivalve mollusks, which are potential food sources of these fishes.
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PMID:Distribution and characteristics of D-amino acid and D-aspartate oxidases in fish tissues. 1254 Dec 99

In this paper, we examined the distribution pattern of D-aspartic acid (D-Asp), as well as D-aspartate oxidase (D-AspO), D-amino acid oxidase (D-AAO), and L-amino acid oxidase (L-AAO) activities in different tissues of frog, Rana esculenta. High concentrations of free D-Asp were found in the testes (0.21+/-0.02 micromol/g b.w), in the liver (0.20+/-0.03 micromol/g b.w), and in the Harderian gland (HG) (0.19+/-0.03 micromol/g b.w). A higher activity of both D-AspO and D-AAO with respect to L-AAO was endogenously present in all examined frog tissues, particularly within the kidney, liver, and brain. Our in vivo experiments, consisting of i.p. injections of 2.0 micromol/g b.w. D-Asp in frogs, revealed that all examined tissues can take up and accumulate D-Asp and that this amino acid specifically triggers D-AspO activity. Indeed, no increase in both D-AAO and L-AAO was found in all frog tissues after D-Asp treatment. The optimum pH for D-AspO activity was around 8.2 and the optimum temperature was about 37 degrees C. Furthermore, its activity linearly increased with increasing D-Asp incubation times. In vitro experiments assaying the substrate specificity of D-AspO indicated that the enzyme had greater affinity for N-methyl-D-aspartate than for D-Asp and D-glutamate. This study provides evidence of the presence of free D-Asp in frog R. esculenta tissues, along with its role in triggering D-AspO activity. These findings suggest that D-AspO could play an essential role in decreasing excessive amounts of D-Asp in frog tissues, a phenomenon that, if left unchecked, could have detrimental physiological effects on the animal.
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PMID:Distribution of free D-aspartic acid and D-aspartate oxidase in frog Rana esculenta tissues. 2010 20