Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.16.3.1 (ceruloplasmin)
 5,074 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The curved plots of 1/v against 1/[S] obtained when caeruloplasmin oxidizes NN-dimethyl-p-phenylenediamine were investigated. The first free-radical oxidation product of caeruloplasmin oxidation of NN-dimethyl-p-phenylenediamine is required for curvature, as straight-line plots were obtained when activities were measured either before appreciable free-radical product had appeared or in the presence of ascorbate, which reduced it back to NN-dimethyl-p-phenylenediamine. 2. In the presence of ascorbate linear reciprocal-plots were obtained with all of the 37 substrates tested. V(max.) values varied over only an eightfold range and those for the 20 p-amino compounds over only a twofold range. K(m) values, however, varied over a 10(4)-fold range. The small range of V(max.) values indicates that the rate-limiting step in caeruloplasmin action is relatively independent of the nature of the substrate. K(m) values suggest that substrates bind primarily by ring electrons, although certain side-chain groups increased the K(m) in a manner unrelated to likely changes of ring-electron densities. A mechanism involving repulsion between negative charges on the substrate and the enzyme was supported by the variation of the K(m) of 5-hydroxyindol-3-ylacetic acid with pH.
 ...
PMID:A method for obtaining linear reciprocal plots with caeruloplasmin and its application in a study of the kinetic parameters of caeruloplasmin substrates. 464 13

A comparative study has been carried out of the oxidation of 5-hydroxytryptamine and related compounds by the oxidase present in the gill plates of Mytilus edulis and of caeruloplasmin, the copper containing oxidase of mammalian plasma. Both preparations oxidized indole derivatives carrying a hydroxyl group in the 4-, 5-, 6-, or 7- position. The oxidation of bufoteni ne was compared with that of its 4- and 6-hydroxy analogues; the 4-hydroxy analogue is psil ocine, a naturally occurring hallucinogenic compound. Bufotenine and the 6-hydroxy analogue were oxidized by both preparations with the formation of brown pigments; psilocine was more rapidly oxidized with the appearance of a blue colour. 4-Hydroxytryptamine and 7-hydroxytryptamine were also oxidized, the former with the formation of a blue compound. The N-1-methyl derivatives of both bufotenine and psilocine were also oxidized. The Mytilus preparation acted also on 4-, 5-, and 7-hydroxytryptophan and on 5-hydroxyindole, none of which was oxidized by caeruloplasmin. The Mytilus enzyme also oxidized 5-hydroxyindoleacetic acid. Paraphenylenediamine, a very good substrate of caeruloplasmin, was much more slowly oxidized by the gill plate enzyme. The evidence suggests that the two enzymes catalyse the same reactions, but that the substrate specificity of the mammalian oxidase is somewhat more restricted. Both enzymes are "hydroxyindole oxidases," not specific for 5-hydroxyindoles alone. Inhibitors of the Mytilus oxidase included inhibitors of copper enzymes but not edetate or carbon monoxide. The action of pig serum on 5-hydroxytryptamine was due to caeruloplasmin and not to amine oxidase.
 ...
PMID:A comparative study of hydroxyindole oxidases. 1910 43