Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Canine Purkinje fibers were isolated by microdissection and analyzed for four enzymes of glycogen metabolism and eight related metabolites. Purkinje fiber glycogen levels were very high, confirming earlier reports. Glycogen synthesizing enzymes, glycogen synthase and UDP glucose pyrophosphorylase, were on the average 47 and 70% higher, respectively, in Purkinje fibers than in myocardium. Phosphorylase activity was approximately equal in the two tissue types, and phosphoglucomutase was 31% lower in Purkinje fibers. The metabolites of glycogen 6-phosphate were all higher in Purkinje fibers (P less than 0.001), but glucose 1,6-bisphosphate was lower by 50%. Phosphocreatine and ATP remained high in Purkinje fibers during 2 min of ischemia, while the phosphocreatine level in myocardium was falling by 75%. The results of this study suggest that the high glycogen synthetic capability, high precursor levels, and overall lower metabolic rate in Purkinje fibers compared with myocardium may explain the much higher glycogen levels.
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PMID:Enzymes and metabolites of glycogen metabolism in canine cardiac Purkinje fibers. 392 32

Glucose 1,6-bisphosphate (Glc-1,6-P(2)) concentration in brain is much higher than what is required for the functioning of phosphoglucomutase, suggesting that this compound has a role other than as a cofactor of phosphomutases. In cell-free systems, Glc-1,6-P(2) is formed from 1,3-bisphosphoglycerate and Glc-6-P by two related enzymes: PGM2L1 (phosphoglucomutase 2-like 1) and, to a lesser extent, PGM2 (phosphoglucomutase 2). It is hydrolyzed by the IMP-stimulated brain Glc-1,6-bisphosphatase of still unknown identity. Our aim was to test whether Glc-1,6-bisphosphatase corresponds to the phosphomannomutase PMM1, an enzyme of mysterious physiological function sharing several properties with Glc-1,6-bisphosphatase. We show that IMP, but not other nucleotides, stimulated by >100-fold (K(a) approximately 20 mum) the intrinsic Glc-1,6-bisphosphatase activity of recombinant PMM1 while inhibiting its phosphoglucomutase activity. No such effects were observed with PMM2, an enzyme paralogous to PMM1 that physiologically acts as a phosphomannomutase in mammals. Transfection of HEK293T cells with PGM2L1, but not the related enzyme PGM2, caused an approximately 20-fold increase in the concentration of Glc-1,6-P(2). Transfection with PMM1 caused a profound decrease (>5-fold) in Glc-1,6-P(2) in cells that were or were not cotransfected with PGM2L1. Furthermore, the concentration of Glc-1,6-P(2) in wild-type mouse brain decreased with time after ischemia, whereas it did not change in PMM1-deficient mouse brain. Taken together, these data show that PMM1 corresponds to the IMP-stimulated Glc-1,6-bisphosphatase and that this enzyme is responsible for the degradation of Glc-1,6-P(2) in brain. In addition, the role of PGM2L1 as the enzyme responsible for the synthesis of the elevated concentrations of Glc-1,6-P(2) in brain is established.
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PMID:Mammalian phosphomannomutase PMM1 is the brain IMP-sensitive glucose-1,6-bisphosphatase. 1892 83