Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dihydroflavin mononucleotide (FMNH2) together with a regenerating enzyme system effectively supported L-tryptophan decyclization by indoleamine 2,3-dioxygenase isolated from murine epididymis. The native murine dioxygenase was a monomeric protein with Mr 40,000 +/- 1000, an apparent pI of 4.9 +/- 0.1, and an optimum pH within the range of 7 to 8. Using FMNH2 with FMN oxidoreductase, the enzyme attained significantly higher activity than the apparent maximal activity obtained by using the other electron donor systems examined (e.g., riboflavin, FAD, tetrahydrobiopterin, methylene blue). A kinetic study with the FMNH2 cofactor suggested the occurrence of a complex reaction (L-tryptophan-FMNH2 interdependency) and a theoretical K'm of 14 microM or a Km of 13 microM was estimated for the substrate. L-Tryptophan 2,3-dioxygenation was competitively inhibited by L-5-hydroxytryptophan with a Ki of 1 microM. The reaction rate was reduced to less than 50% of that of the control in the presence of superoxide dismutase and was decreased to 3% of the control in the absence of catalase. Thus, superoxide anion does not appear to be the only form of O2 participating in the reaction. However, these data indicate that the activation of molecular oxygen is an essential factor for an optimum catalysis and a mechanism of FMNH2-dependent oxygenation of L-tryptophan by murine indoleamine 2,3-dioxygenase.
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PMID:Utilization of dihydroflavin mononucleotide and superoxide anion for the decyclization of L-tryptophan by murine epididymal indoleamine 2,3-dioxygenase. 282 Mar 8

Rat FAD-dependent sulfhydryl oxidase was purified; partial sequencing indicated that it was homologous to human quiescin Q6. A cDNA (GenBank accession no. AF285078) was cloned from rat seminal vesicles, and active recombinant sulfhydryl oxidase was expressed in Chinese hamster ovary epithelial cells. This 2472-nucleotide cDNA has an open reading frame of 1710 base pairs, encoding a protein of 570 amino acids including a 32-amino acid leader sequence and two potential sites for N-glycosylation. One of them is used and the 64,000 M(r) purified protein was transformed to 61,000 by the action of endoglycosidase F. Northern blotting and reverse transcription-polymerase chain reaction analyses showed that there were small amounts of sulfhydryl oxidase in the rat testis, prostate, lung, heart, kidney, spleen, and liver, and that the gene was highly expressed in seminal vesicles and epididymis. Rat sulfhydryl oxidase cDNA corresponds to the human cell growth inhibiting factor cDNA, which could be a differently spliced form of quiescin Q6. Comparing sulfhydryl oxidase sequences with those of human quiescin Q6 and mammalian and Caenorhabditis elegans quiescin Q6-related genes established the existence of a new family of FAD-dependent sulfhydryl oxidase/quiescin Q6-related genes containing protein-disulfide isomerase-type thioredoxin and yeast ERV1 domains.
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PMID:Rat seminal vesicle FAD-dependent sulfhydryl oxidase. Biochemical characterization and molecular cloning of a member of the new sulfhydryl oxidase/quiescin Q6 gene family. 1127 90