Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of the succinate dehydrogenase-coenzyme Q10 reductase from 120 diabetic patients was significantly lower (P less than 0.001) and the per cent deficiency was significantly higher (P less than 0.001) than that of the controls. The diabetes of 37 patients was controlled by diet; the enzyme activity was lower (P less than 0.001) and the deficiency was higher (P less than 0.02) than for controls. In decreasing effectiveness, Dymelor, Glyburide, Phenformin and Tolazamide inhibited the COQ10-enzyme, NADH-oxidase. Tolbutamide, Glypizide, and Chlorpropamide were noninhibitory to succinoxidase and NADH-oxidase. Patients receiving Tolazamide and Phenformin showed a higher incidence (P less than 0.001 to P less than 0.05) of COQ10-deficiency than patients controlled by diet or normal controls. Certain diabetic patients controlled by diet may have a deficiency of COQ10 which may be enhanced by the inhibition by certain commonly used antidiabetic drugs of COQ10-enzymes. A deficiency of COQ10 in the pancreas could impair bioenergetics, the generation of ATP, and the biosynthesis of insulin.
 ...
PMID:Bioenergetics in clinical medicine. XI. Studies on coenzyme Q and diabetes mellitus. 107 May 15

Succinate dehydrogenase activities in homogenates of rat and ob/ob mouse pancreatic islets were only 13% of the activities in homogenates of liver and were also several times lower than in homogenates of pancreatic acinar tissue. This indicates that the content of mitochondria in pancreatic islet cells is very low. The very low activity of succinate dehydrogenase is in agreement with the low mitochondrial volume in the cytoplasmic ground substance of pancreatic islet cells as observed in morphometric studies. This may represent the poor equipment of pancreatic islet cells with electron transport chains and thus provide a regulatory role for the generation of reducing equivalents and chemical energy for the regulation of insulin secretion. The activities of succinate dehydrogenase in tissue homogenates of pancreatic islets, pancreatic acinar tissue, and liver were significantly inhibited by malonate and diazoxide but not by glucose, mannoheptulose, streptozotocin, or verapamil. Tolbutamide inhibited only pancreatic islet succinate dehydrogenase significantly, providing evidence for a different behavior of pancreatic islet cell mitochondria. Therefore diazoxide and tolbutamide may affect pancreatic islet function through their effects on succinate dehydrogenase activity. The activities of alpha-glycerophosphate dehydrogenase in homogenates of pancreatic islets and liver from rats and ob/ob mice were in the same range, while activities in homogenates of pancreatic acinar tissue were lower. None of the test agents affected alpha-glycerophosphate dehydrogenase activity. Thus the results provide no support for the recent contention that alpha-glycerophosphate dehydrogenase activity may be critical for the regulation of insulin secretion.
 ...
PMID:Characterization of succinate dehydrogenase and alpha-glycerophosphate dehydrogenase in pancreatic islets. 636 Jan 62

We examined three primary variables in the preparation of human liver microsomes. In three experiments, each using three livers, we manipulated 1) the force of the first centrifugation (9,000, 10,500, or 12,000g); 2) the presence of sucrose in the homogenization buffer; and 3) the number of homogenizing strokes (6, 8, or 10). Sedimentation plots for the marker enzymes succinate dehydrogenase, NADPH cytochrome P450 reductase (reductase), and glutathione S-transferase in the resulting premicrosomal, microsomal, and cytosolic fractions suggest that enhanced purity of microsomes can be obtained by reducing force of centrifugation, including sucrose, and increasing the number of homogenization strokes. Each microsomal fraction was also assayed for protein content, cytochrome P450, NADH cytochrome b(5) reductase, cytochrome b(5), absorbance at 420, p-nitrophenol hydroxylation, tolbutamide hydroxylation, dextromethorphan N- and O-demethylation, glucuronidation of morphine and 1-naphthol, and ester cleavage of p-nitrophenolacetate. These microsomal indicators were ranked and tested for statistical differences. The use of 9000g statistically increased optimal recovery (per gram of liver) and specific activity (per milligram of protein). The inclusion of sucrose improved activity specific to reductase activity. Ten homogenization strokes improved activity specific to reductase activity. Substrate-dependent activities of dextromethorphan O-demethylation to dextrorphan and the N-demethylation of l-alpha-acetylmethadol (LAAM) to norLAAM and dinorLAAM were compared in microsomes prepared with or without sucrose and microsomes prepared using 9,000 or 12,000g force, respectively. No significant differences were found in the concentration-dependent activities. Variation of the methods used to prepare human liver microsomes can significantly affect the recovery and specific activity of microsomal components; however, they do not appear to affect enzyme kinetics.
 ...
PMID:Variables in human liver microsome preparation: impact on the kinetics of l-alpha-acetylmethadol (LAAM) n-demethylation and dextromethorphan O-demethylation. 1118 2