Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.17.3.2 (xanthine oxidase)
 8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Very little is known of the metabolism of copper on a molecular level. For example, there is no evidence of an oxidative breakdown of Cu(I)-thionein leading to Cu(II). Thus it was of interest to use L- and D-amino-acid oxidases, amino oxidase and galactose oxidase to control the oxidation of Cu(I)-thionein by enzymically generated H2O2. In the presence of these enzymes Cu(II) was generated in each case. In a more detailed study the Cu(I)-thiolate chromophores of Cu-thionein were oxidized in the presence of xanthine oxidase as deduced from spectrometrical measurements using EPR and circular dichroism. Unlike Cu2Zn2-superoxide dismutase catalase inhibited the oxidative cleavage, suggesting peroxide as the actual oxidizing agent. Possibly there is an enzymic oxidative pathway for the generation of biologically important Cu(II).
 ...
PMID:Oxidation of Cu(I)-thionein by enzymically generated H2O2. 654 80

Enzymatic reactions are important for the synthesis of chiral molecules. One factor limiting synthetic applications of enzymes is the poor aqueous solubility of numerous substrates. To overcome this limitation, enzymes can be used directly in organic solvents; however, in nonaqueous media enzymes usually exhibit only a fraction of their aqueous-level activity. Salt-activation, a technique previously demonstrated to substantially increase the transesterification activity of hydrolytic enzymes in organic solvents, was applied to horse liver alcohol dehydrogenase, soybean peroxidase, galactose oxidase, and xanthine oxidase, which are oxidoreductase and oxygenase enzymes. Assays of the lyophilized enzyme preparations demonstrated that the presence of salt protected enzymes from irreversible inactivation. In organic solvents, there were significant increases in activity for the salt-activated enzymes compared to nonsalt-activated controls for every enzyme tested. The increased enzymatic activity in organic solvents was shown to result from a combination of protection against inactivation during the freeze-drying process and other as-yet undetermined factors.
 ...
PMID:Salt-activation of nonhydrolase enzymes for use in organic solvents. 1475 64