Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our laboratory recently isolated free PQQ (2,7,9-tricarboxy-pyrroloquinoline quinone, methoxatin), a bacterial redox cofactor, from red cells, neutrophils, serum and milk and found free PQQ in CSF, synovial fluid and bile. The metabolism and functions of PQQ and ascorbate may be coupled. Physiologically, free PQQ catalyzes dioxygen-superoxide interconversion, and participates in both superoxide generation (respiratory burst) and scavenging (cell protection). Using a labeled aromatic o-diamine, superoxide formation by activated neutrophils was inhibited and the labeled phenazine adduct of PQQ could be isolated from the inhibited cells (Karnovsky et al., 1992). PQQ may convert xanthine oxidase to xanthine dehydrogenase (XD) and could be the physiological coenzyme of XD. PQQ plus copper, form a potent amine-oxidizing system. Shah et al., 1992 found that PQQ-Cu2+ catalyzes the oxidation of epsilon-amino groups in collagen and elastin. Rucker's lab (Smidt et al., 1991) has found that PQQ may be a vitamin for mouse pups. Watanabe et al., 1988 and Nishigori et al., 1989, showed that injected PQQ protects animals against oxidative stress injury. PQQ's in vivo antioxidant action, spares reduced glutathione. PQQ, as an actively transported organic anion, concentrates in cells. In other experiments (Aizenman et al., 1992), PQQ protected neurons against the neurotoxin action of the glutamate-receptor against NMDA. We shall consider possible roles for PQQ in the biosynthesis of nitric oxide (NO, endothelium-derived relaxing factor, EDRF) from L-arginine and in NO removal by superoxide. NO has now been linked to the inhibition of osteoclastic bone resorption.
 ...
PMID:Is the antioxidant, anti-inflammatory putative new vitamin, PQQ, involved with nitric oxide in bone metabolism? 840 96

1. In the present study, endothelium-derived relaxing factor (EDRF/nitric oxide (NO)), conversion of big endothelin (ET)-1 to endothelin-1 (ET-1) and the role of reactive oxygen species were investigated in kidneys isolated from glycerol (GLY)-pretreated rabbits. 2. Acetylcholine (ACh)-induced vasodilation that is due to the release of EDRF/NO is significantly decreased, whereas big ET-1-induced vasoconstriction was increased in kidneys isolated from GLY-pretreated rabbits. 3. Pretreatment of rabbits with the xanthine oxidase inhibitor allopurinol and the NO precursor L-arginine reversed the inhibition of ACh-induced vasodilation due to GLY and protects the kidney vasculature. 4. Big ET-1, but not ET-1, responses were found to be significantly increased in kidneys isolated from GLY-pretreated rabbits. This increase is attributed to the higher conversion rate of big ET-1 to ET-1 because the ET-converting enzyme (ECE) inhibitor phosphoramidon, at a concentration of 10(-6) mol/L, causes an inhibition in the response to big ET-1 by 52.6% in normal kidneys, whereas this inhibition with the same concentration of phosphoramidon was found to be significantly decreased in kidneys isolated from GLY-pretreated rabbits. 5. The non-selective NO synthase inhibitor N(G)-nitro-L- arginine methyl ester (L-NAME) caused a significant potentiation in the vasoconstrictor response to ET-1 in normal isolated perfused rabbit kidneys. However, L-NAME did not alter the responses to ET-1 in GLY-pretreated kidneys. 6. These results indicate that accumulation of reactive oxygen species causes an inhibition in NO bioavailability. Increased conversion of big ET-1 to ET-1 may also contribute to the mechanism of vascular damage due to GLY.
 ...
PMID:Effect of glycerol on endothelium-derived factors in the vasculature of the rabbit kidney. 1209 99