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)

Aldehyde dehydrogenase from Pseudomonas testosteroni was purified to homogeneity. The enzyme has a pH optimum of 8.2, uses a wide range of aldehydes as substrates and cationic dyes (Wurster's blue, phenazine methosulphate and thionine), but not anionic dyes (ferricyanide and 2.6-dichloroindophenol), NAD(P)+ or O2, as electron acceptors. Haem c and pyrroloquinoline quinone appeared to be absent but the common cofactors of molybdenum hydroxylases were present. Xanthine was not a substrate and allopurinol was not an inhibitor. Alcohols were inhibitors only when turnover of the enzyme occurred in aldehyde conversion. The enzyme has a relative molecular mass of 186,000, consists of two subunits of equal size (Mr 92,000), and 1 enzyme molecule contains 1 FAD, 1 molybdopterin cofactor, 4 Fe and 4 S. It is a novel type of NAD(P)+-independent aldehyde dehydrogenase since its catalytic and physicochemical properties are quite different from those reported for already known aldehyde-converting enzymes like haemoprotein aldehyde dehydrogenase (EC 1.2.99.3), quino-protein alcohol dehydrogenases (EC 1.1.99.8) and molybdenum hydroxylases.
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PMID:NAD(P)+-independent aldehyde dehydrogenase from Pseudomonas testosteroni. A novel type of molybdenum-containing hydroxylase. 360 27

5-Pyridoxic-acid oxygenase, a cytoplasmic enzyme formed when Arthrobacter Cr-7 is grown with pyridoxine as a sole source of carbon and nitrogen, was purified about 190-fold to homogeneity from fully induced cells. The enzyme catalyzes Reaction a, (Formula: see text) the essential ring-opening step in the degradation of pyridoxine, and provides a second example of an FAD-dependent oxygenase that adds both two hydrogen and two oxygen atoms to its substrate. 5-Pyridoxic-acid oxygenase has an isoelectric point of 4.6, functions optimally between pH 7 and 8, appears to contain a single subunit of Mr = 51,000 and one FAD (but no iron) per subunit, and is readily resolved by precipitation with ammonium sulfate at pH 3.0. FMN and riboflavin do not replace FAD as coenzyme, but their presence enhances a normally minor side reaction (Reaction b) NAD(P)H + H+ + O2----NAD(P)+ + H2O2 (b) catalyzed by the holoenzyme. Reaction b also is enhanced when the poorly utilized analogues, 3-hydroxy-2-methylpyridine-5-carboxylic acid or NADH, replace 5-pyridoxic acid or NADPH, respectively, as substrates in Reaction a. Each of the enzymes required in two different pathways for degradation of pyridoxine to anabolic intermediates has now been studied. A comparison of these two pathways and their enzymes is provided.
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PMID:Enzymes of vitamin B6 degradation. Purification and properties of 5-pyridoxic-acid oxygenase from Arthrobacter sp. 377 66

The reductase enzymes in Nitrosomonas and Nitrobacter were studied under anaerobic conditions when the oxidase enzymes were inactive. The most effective electron-donor systems for nitrate reductase in Nitrobacter were reduced benzyl viologen alone, phenazine methosulphate with either NADH or NADPH, and FMN or FAD with NADH. Nitrite and hydroxylamine reductases were found in both nitrifying bacteria, and optimum activity for each enzyme was obtained with NADH or NADPH with either FMN or FAD. The product of both these enzymes was identified as ammonia. In extracts of Nitrosomonas the ammonia was further utilized by an NADPH-specific glutamate dehydrogenase. (15)N-labelled nitrite, hydroxylamine and ammonia were rapidly incorporated into cell protein by Nitrosomonas, and Nitrobacter in addition incorporated [(15)N]nitrate. Relatively gentle methods of cell disruption were compared with ultrasonic treatment, to enable a more exact study to be undertaken of the intracellular distribution of the oxidase and reductase enzymes. The functional relationship of these opposing enzyme systems in the nitrifying bacteria is considered.
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PMID:Properties of some reductase enzymes in the nitrifying bacteria and their relationship to the oxidase systems. 438 32

The flavin prosthetic group (FAD) of the aromatic hydroxylases melilotate hydroxylase (EC 1.14.13.4) and phenol hydroxylase (EC 1.14.13.7) was replaced by 1-deaza-FAD (carbon substituted for nitrogen at position 1). Neither modified enzyme could hydroxylate its substrate, both catalyzed the oxidation of NAD(P)H to NAD(P)+ and H2O2. The rate of the reduction of the enzymes by NAD(P)H was increased by the binding of substrate. Both enzymes formed a detectable flavin C(4a) hydroperoxide intermediate upon reaction of the reduced enzyme-substrate complex with oxygen. Reduced 1-deaza-FAD phenol hydroxylase also showed a detectable C(4a) hydroperoxide intermediate when reacted with oxygen in the absence of substrate. The C(4a) hydroperoxide of 1-deaza-FAD phenol hydroxylase, in the absence of phenol, decayed to an intermediate which showed a perturbed oxidized enzyme spectrum, Eox. This intermediate in turn decayed to give the original oxidized enzyme. In the presence of phenol, a second oxidized species with a perturbed spectrum, intermediate X, was apparent after formation of the flavin C(4a) hydroperoxide and before Eox formation. Steady state kinetic analysis of 1-deaza-FAD phenol hydroxylase demonstrated that the Eox to Eox conversion was not in the catalytic cycle. During turnover Eox was reduced by NADPH.
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PMID:Reactions of 1-deaza-FAD-substituted phenol hydroxylase and melilotate hydroxylase. 669 23

The aim of the present study is to compare normal and tumoral pancreatic islet cells in terms of both the activity of selected cytosolic and mitochondrial enzymes participating to nutrient catabolism and the intrinsic properties of FAD-glycerophosphate dehydrogenase. The activity of the glycolytic enzymes hexokinase and lactate dehydrogenase was higher in tumoral (RINm5F) than normal islet cells. The opposite was seen for glutamate decarboxylase, glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase, glutamate dehydrogenase, 2-ketoglutarate dehydrogenase and FAD-glycerophosphate dehydrogenase (m-GDH). These findings are consistent with the high rates of glycolysis and protein synthesis seen in tumoral islet cells compared with normal islet cells, which favour mitochondrial oxidative events associated with the catabolism of D-glucose and amino acids. The intrinsic catalytic properties of m-GDH were comparable, albeit not identical, in normal and tumoral islet cells. Since a deficiency of m-GDH in pancreatic islets may represent a contributing factor in the pathogenesis of non-insulin-dependent diabetes, it is proposed that RINm5F cells may readily yield sufficient islet m-GDH for purification and further gene cloning.
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PMID:Activity of cytosolic and mitochondrial enzymes participating in nutrient catabolism of normal and tumoral islet cells. 776 86

The mitochondrial FAD-linked enzyme glycerophosphate dehydrogenase plays a key role in the pancreatic B-cell glucose sensing device. In the present study, the activity of this enzyme was examined in islets of fa/fa rats in which inherited diabetes mellitus is associated with obesity, hyperinsulinism and severe insulin resistance. The specific activity of both FAD-linked glycerophosphate dehydrogenase and glutamate dehydrogenase were decreased in islet and liver homogenates prepared from fa/fa, as compared to Fa/Fa, rats, this coinciding with a low ratio between glutamateoxalacetate and glutamate-pyruvate transaminase activity in both islet and liver extracts, islet hyperplasia, hyperinsulinemia and hepatic steatosis in the hyperglycemic fa/fa rats. It is speculated that a low activity of FAD-linked glycerophosphate dehydrogenase in the pancreatic B-cell may participate to the perturbation of glucose homeostasis in fa/fa rats, like in other animal models of non-insulin-dependent diabetes mellitus.
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PMID:Impaired FAD-glycerophosphate dehydrogenase activity in islet and liver homogenates of fa/fa rats. 783 41

This study aimed to compare the metabolic and secretory responses of pancreatic islets from animals with non-insulin-dependent diabetes to D-glucose with the effects of the methyl esters of succinic acid (SME) and glutamic acid (GME). The insulin secretory response to D-glucose was impaired in islets from rats with diabetes which was either inherited (Goto-Kakizaki (GK) rats) or acquired (streptozotocin-treated (STZ) rats). This coincided with a preferential alteration of oxidative relative to total glycolysis in intact islets and a selective defect of FAD-linked mitochondrial glycerophosphate dehydrogenase (m-GDH) in islet homogenates. This enzymatic defect was also found in purified B cells from STZ rats. It contrasted both with unaltered activities of glutamate dehydrogenase and succinate dehydrogenase in the islets of diabetic animals and with a normal or even increased activity of m-GDH in the livers of GK and STZ rats. The oxidation of [1,4-14C]SME and [U-14C]GME appeared decreased in islets of GK or STZ animals when compared with control rats, but no significant difference between control and diabetic rats was observed when the oxidative data were expressed relative to the rate of [U-14C]GME hydrolysis. Nevertheless, the absolute values for insulin release evoked by a non-metabolized analogue of L-leucine (BCH), by SME and by the association of BCH with either SME or GME were invariably lower in islets of GK and STZ rats than in those of control animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pancreatic islet response to dicarboxylic acid esters in rats with type 2 diabetes: enzymatic, metabolic and secretory aspects. 784 32

Islets were isolated by automatic digestion from non-diabetic cadaveric organ donors and from Type 2 (non-insulin-dependent) diabetic subjects. The activity of FAD-glycerophosphate dehydrogenase, but not that of either glutamate dehydrogenase, glutamate-oxalacetate transaminase or glutamate-pyruvate transaminase, was lower in Type 2 diabetic patients than control subjects. Hexokinase, glucokinase and glutamate decarboxylase activities were also measured in islets from control subjects. The utilization of D-[5-3H]glucose, oxidation of D-[6-14C]glucose and release of insulin evoked by D-glucose were all lower in Type 2 diabetic patients than control subjects. The secretory response to the combination of L-leucine and L-glutamine appeared less severely affected. Islets from Type 2 diabetic patients may thus display enzymatic, metabolic and secretory anomalies similar to those often observed in animal models of Type 2 diabetes, including a deficiency of beta-cell FAD-linked glycerophosphate dehydrogenase, the key enzyme of the glycerol phosphate shuttle.
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PMID:Enzymatic, metabolic and secretory patterns in human islets of type 2 (non-insulin-dependent) diabetic patients. 816 52

In vitro, streptozotocin (1.0-2.0 mM) fails to exert any immediate effect on the activity of FAD-glycerophosphate dehydrogenase in either pancreatic islet homogenate or freshly isolated intact islets. However, when injected in vivo, streptozotocin (40 mg/kg body weight) lowers the specific activity of the FAD-linked enzyme in islet homogenates within 24 h, whilst causing little change in 2-ketoglutarate dehydrogenase and increasing glutamate dehydrogenase islet activity. In animals which became frankly hyperglycaemic as the result of the injection of streptozotocin, the activity of islet FAD-glycerophosphate dehydrogenase, measured 2 weeks after administration of the B-cell cytotoxic agent, was decreased to 10-20% of its control value. Neither insulin treatment nor riboflavin supplementation affected this enzymic defect. Even when the animals injected with streptozotocin remained virtually euglycaemic, the activity of islet FAD-glycerophosphate dehydrogenase was markedly decreased. This coincided with a preferential impairment of aerobic glycolysis, as judged from the ratio between D-[3,4-14C]glucose oxidation and D-[5-3H] glucose utilization by the islets. It is proposed, therefore, that the administration of sub-diabetogenic amounts of streptozotocin to adult rats represents an alternative and easier approach to the study of B-cell dysfunction in this model of type 2 (non-insulin-dependent) diabetes than does streptozotocin injection in neonatal rats.
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PMID:Streptozotocin-induced FAD-glycerophosphate dehydrogenase suppression in pancreatic islets. Relationship with the severity and duration of hyperglycaemia and resistance to insulin or riboflavin treatment. 832 33

The activity of FAD-linked glycerophosphate dehydrogenase (m-GDH), as well as that of glutamate dehydrogenase and both glutamate-oxalacetate and glutamate-pyruvate transaminases, were measured in islet, liver, and splenocyte homogenates from 6- to 7-week-old female nonobese diabetic mice (NOD) and age- and sex-matched control mice. Despite incipient insulitis and euglycemia, the NOD mice displayed both high islet insulin content and elevated insulinemia. The activity of m-GDH, expressed relative to protein content, was not decreased in islets of NOD mice, despite the fact that such a specific activity is lower in splenic lymphocytes than islet cells. In liver homogenates, the activity of m-GDH was even higher in NOD than control mice. It is proposed, therefore, that in this model of insulin-dependent diabetes no primary decrease in islet m-GDH activity occurs, at variance with the situation recently documented in several animal models of non-insulin-dependent diabetes.
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PMID:FAD-linked glycerophosphate dehydrogenase activity in islets, liver, and splenocytes of NOD mice. 837 36


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