Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.12.7.2 (hydrogenase)
 3,522 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatocyte nodules that persist throughout chemical carcinogenesis are linked to carcinomas both as one site at which hepatomas are seen to arise and as a tissue which shows more than a dozen significant protein changes also found in liver cancers. In view of the differential stimulus to growth of these persistent nodules by progesterone, progesterone metabolism and binding to the microsomes of nodules and hepatomas were studied. Progesterone metabolizing enzyme activities in nodule microsomes showed striking shifts with a 42% decrease in 16 alpha-hydroxylase activity and a 2- to 3-fold increase in 6 beta-hydroxylase activity compared to control levels. Hepatomas had a dramatic 20-fold increase relative to nodules or controls in the reductive pathway for progesterone metabolism as measured by delta 4-5 alpha-hydrogenase activity. The rate and saturation of the specific binding of progesterone to microsomes of nodules and liver cancers were significantly decreased when compared either to the tissue surrounding the nodules or to their respective control microsomes. This change in progesterone binding of nodular microsomes may relate to an altered balance of progesterone content and its metabolites in the nodular cells or to alterations in the microsomal membrane binding site. The functional significance of reduced binding of progesterone for liver carcinogenesis is thus open to further inquiry.
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PMID:Changes in progesterone binding and metabolism in liver microsomes from persistent hepatocyte nodules and hepatomas in male rats. 394 Feb 12

Nickel has been shown to be an essential trace element involved in the metabolism of several species of bacteria, archea, and plants. In these organisms, nickel is involved in enzymes that catalyze both non-redox (e.g., urease, glyoxalase I) and redox (e.g., hydrogenase, carbon monoxide dehydrogenase, superoxide dismutase) reactions, and proteins involved in the transport, storage, metallocenter assembly, and regulation of nickel concentration have evolved. Studies of structure/function relationships in nickel biochemistry reveal that cysteine ligands are used to stabilize the Ni(III/II) redox couple. Certain nickel compounds have also been shown to be potent human carcinogens. A likely target for carcinogenic nickel is nuclear histone proteins. Here we present X-ray absorption spectroscopic studies of a model Ni peptide designed to help characterize the structure of the nickel complexes formed with histones and place them in the context of nickel structure/function relationships, to gain insights into the molecular mechanism of nickel carcinogenesis.
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PMID:Use of XAS for the elucidation of metal structure and function: applications to nickel biochemistry, molecular toxicology, and carcinogenesis. 1242 16