| atrial premature complexes | Premature contractions of the heart arising from an ectopic atrial focus. With ventricular premature complexes, they represent one of the most common causes of irregular pulse. They are more apt to occur if there is atrial or conduction system disease such as left atrial enlargement in mitral stenosis. In community prospective studies, atrial premature complexes are not related to sudden death, as are ventricular premature beats in coronary disease. (12 Dec 1998) |
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| cardiac complexes, premature | Premature contractions of the heart that are independent of the normal rhythm and arise in response to an impulse in some part of the heart other than the sinoatrial node. (12 Dec 1998) |
| ventricular premature complexes | Premature contractions of the ventricle, the most common of all arrhythmias. In the absence of heart disease, they are not of great clinical significance, but in patients with coronary disease, they represent a constant danger of ventricular tachycardia or fibrillation and sudden death. The longer-term prognosis for asymptomatic, healthy subjects with frequent and complex ectopy is similar to that for the healthy united states population. (12 Dec 1998) |
| respiratory enzyme complexes | <biochemistry> The enzymes that make up the respiratory chain: NADH Q reductase, succinate Q reductase, cytochrome reductase, cytochrome C and cytochrome oxidase. (18 Nov 1997) |
| multienzyme complexes | Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates; may involve simply a transfer of water molecules of hydrogen atoms or be associated with large supramolecular structures such as mitochondria or ribosomes. (12 Dec 1998) |
| ATP | <biochemistry> A nucleotide present in all living cells which serves as an energy source for many metabolic processes and is required for ribonucleic acid synthesis. (06 May 1997) |
| ATP citrate lyase | ATP citrate (pro-3S)-lyase |
| ATP citrate (pro-3S)-lyase | <enzyme> An enzyme that, in the presence of ATP and CoA, catalyses the cleavage of citrate to yield acetyl CoA, oxaloacetate, ADP, and orthophosphate. This reaction represents an important step in fatty acid biosynthesis. Chemical name: ATP:citrate oxaloacetate-lyase ((pro-S)-CH2COO(-)--acetyl-CoA) (ATP-dephosphorylating) Registry number: EC 4.1.3.8 Synonym: citrate cleavage enzyme. (12 Dec 1998) |
| ATP cobalamin adenoxyltransferase | <enzyme> An enzyme that catalyses the reaction of ATP, water, and cobalamin to form orthophosphate, pyrophosphate, and adenoxylcobalamin. Adenosylcobalamin is required by methylmalonyl-CoA mutase. A deficiency of ATP cobalamin adenosyltransferase will lead to methylmalonic acidemia. (05 Mar 2000) |
| ATP-corrinoid adenosyltransferase | <enzyme> Shares significant homology and functional similarity with btur of escherichia coli and cobo of pseudomonas denitrificans; do not confuse with product of coba gene of pseudomonas, which produces uroporphyrin-iii c-methyltransferase; 196 aa residues, mw 22-25 kD; genbank l08890 Registry number: EC 2.5.1.- Synonym: coba protein, coba gene product (26 Jun 1999) |
| ATP dependent 26S protease | <enzyme> Degrades proteins conjugated to ubiquitin; composed of cf-1,cf-2, and cf-3; cf-2 (also known as 240-kD proteasome inhibitor) is identical to aminolevulinic acid dehydratase Registry number: EC 3.4.99.- Synonym: 26s protease, 26 s proteasome complex, 26s proteasome (26 Jun 1999) |
| ATP-dependent DNA strand transferase | <enzyme> From human cell nuclei; catalyses strand exchange between homologous DNA sequences; magnesium dependent, requires ATP hydrolysis Registry number: EC 2.7.7.- Synonym: ATP-dep-DNA-str trnsfase (26 Jun 1999) |
| ATP-diphosphatase | <enzyme> An enzyme that catalyses breakdown of ATP to AMP, usually extracted from plants, but aortic and placental forms have also been described. (18 Nov 1997) |
| ATP-monophosphatase | <enzyme> A group of enzymes which catalyze the hydrolysis of ATP coupled with another function such as transporting calcium across a membrane. These enzymes may be dependent on calcium, magnesium, anions, h+, or DNA. Chemical name: ATP phosphohydrolase Registry number: EC 3.6.1.3 (12 Dec 1998) |
| ATP phosphoribosyltransferase | <enzyme> An enzyme that catalyses the first step of the pathway for histidine biosynthesis in salmonella typhimurium. ATP reacts reversibly with 5-phosphoribosyl-1-pyrophosphate to yield n-1-(5'-phosphoribosyl)-ATP and pyrophosphate. Chemical name: 1-(5-Phospho-D-ribosyl)-ATP:pyrophosphate phospho-alpha-D- ribosyltransferase Registry number: EC 2.4.2.17 (12 Dec 1998) |