Adenine succinyl

The mean recovery of 100% (range 63% for orotidine to 124% for 2,8 dihydroxy-adenine) is probably acceptable similarly, the mean intra-laboratory imprecision ( V =11.9%, range 6.0 for pseudouridine to 21.9% for succinyl adenosine) is likely to be adequate for most clinical applications. However, the interlaboratory imprecision is somewhat disturbing mean CV = 126% (range 16.8% for pseudouridine to 295% for orotidine). This variation indicates the need to harmonise standardisation. 

Other contacts to the vicinal OH groups and adenine ring of 5-deoxyadenosine and the acyl-carbonyl and carboxylate groups of succinyl-CoA are also shown. Data obtained from PDB 4req. ° (b) A mechanism for the action of MCM. 

Low et al. (2004) have proposed a model to explain thioacetamide-induced hepatotox-icity and cirrhosis in rat livers. The pathways of thioacetamide-induced liver fibrosis were found to be initiated by thioacetamide S-oxide derived from the biotransformation of thioacetamide by the microsomal flavin-adenine nucleotide containing monooxygenase and cytochrome P450 systems and involve oxidative stress and depletion of succinyl-CoA, thus affecting heme and iron metabolism. Karabay et al. (2005) observed such hepatic damage in rats with elevation of total nitrite level in livers and decrease in arginase activity. The authors have reported that nitrosative stress was essentially the critical factor in thioacetamide-induced hepatic failure in rats. 

Figure 11.2 Reaction sequences catalyzed by 2-oxoacid dehydrogenase complex Pyruvate dehydrogenase complex (PDC) and a-ketoglutarate dehydrogenase complex (aKGDC) catalyze the oxidative decarboxylation of pyruvate (R = CH3) and a-ketoglutarate (R = CH2CH2COOH) to Acetyl-CoA and succinyl CoA respectively. Three component enzymes 2-oxoacid (pyruvate/a-ketoglutarate) decarboxylase, lipoate acetyltransferase/succinyltransferase, dihydrolipoate dehydrogenase as well as five cofactors, namely (1) thiamine pyrophosphate (TPP) and its acylated form, (2) lipoamide (LipS2), reduced form and acylated form, (3) flavin adenine dinucleotide (FAD) and its reduced form, (4) nicotinamide adenine dinucleotide (NAD ) and its reduced form, and (5) coenzyme A (CoASH) and its acylated product are involved.

Decarboxylation removal of a carboxyl group as CO2, from a ketoacid or from an amino acid. D. of ketoacids occurs several times in the course of the TH-carboxylic acid cycle (see). TTie D. of P-ketoacids often occurs spontaneously. In biological systems the oxidative D. of a-ketoacids requires coenzymes such as thiamin pyrophosphate, lipoic acid, coenzyme A, flavin adenine dinucleotide or nicotinamide adenine dinucleotide. Oxidative D. of Pyruvate (see) to ace-tyl-CoA and of a-ketoglutarate to succinyl-CoA are nodes at which many metabolic pathways cross. D. of amino acids is catalysed by Pyridox phosphate (see) enzymes. 

Both phosphate ions and one of the adenine nucleotides must be added to freshly prepared mitochondrial suspensions (in sucrose or dilute KCl) for citric-acid cycle oxidations to proceed at maximal velocity. The conversion of succinyl CoA to succinate is one of several processes which depend upon both inorganic phosphate (Pi) and ADP. The formal equation for this conversion is as follows ... 

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