| myosin light chain kinase | <enzyme> An enzyme that phosphorylates myosin light chains in the presence of ATP to yield myosin-light chain phosphate and ADP, and requires calcium and calmodulin. The 20-kD light chain is phosphorylated more rapidly than any other acceptor, but light chains from other myosins and myosin itself can act as acceptors. The enzyme plays a central role in the regulation of smooth muscle contraction. Chemical name: ATP:myosin-light-chain O-phosphotransferase Registry number: EC 2.7.1.117 (12 Dec 1998) |
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| haemolytic chain | The haemolysis that occurs when complement is activated by the previously formed union of erythrocytes and specific antibody. (05 Mar 2000) |
| H chain | <protein> Heavy chain of immunoglobulin, see IgG, IgM, etc. (18 Nov 1997) |
| heavy chain | <protein> In general, the larger polypeptide in a multimeric protein. Thus the immunoglobulin heavy chain is of 50 kD, the light chain of 22 kD, whereas in myosin the heavy chain is very much larger (220 kD) than the light chains (~20 kD). (18 Nov 1997) |
| heavy chain disease | A disorder of immunoglobulin synthesis in which large quantities of abnormal heavy chains are excreted in the urine. The amino acid sequences of the n- (amino-) terminal regions of these chains are normal, but they have a deletion extending from part of the variable domain through the first domain of the constant region, so that they cannot form cross-links to the light chains. The defect arises through faulty coupling of the variable (v) and constant (c) region genes. (12 Dec 1998) |
| xenobiotic medium chain fatty acid - coenzyme A ligase | <enzyme> Partial amino acid sequence of enzyme from bovine liver mitochondria given I first source; has high sequence homology to human and rat sa protein Registry number: EC 6.2.1.- Synonym: xl-i ligase, xl-i carboxylic acid - CoA ligase (26 Jun 1999) |
| short chain | In bacteriology, a string of two to eight cells. (05 Mar 2000) |
| short-chain acyl-CoA dehydrogenase | See: acyl-CoA dehydrogenase (NADPH+). (05 Mar 2000) |
| short-chain beta-hydroxyacyl-CoA dehydrase | <enzyme> Forms trans-2-enoyl-CoA; maximal activity with trans-2-hexenoyl-CoA, followed by crotonyl-CoA; not the same as EC 4.2.1.17 Registry number: EC 4.2.1.- Synonym: beta-hydroxybutyryl-CoA dehydrase, short-chain beta-hydroxyacyl-coenzyme a dehydrase (26 Jun 1999) |
| side chain | A chain of noncyclic atoms linked to a benzene ring, or to any cyclic chain compound, the atoms of an alpha-amino acid other than the alpha-carboxyl group, the alpha-amino group, the alpha-carbon, and the hydrogen attached to the alpha-carbon. (05 Mar 2000) |
| side-chain theory | Ehrlich postulated that cells contained surface extensions or side chains (haptophores) that bind to the antigenic determinants of a toxin (toxophores); after a cell is stimulated, the haptophores are released into the circulation and become the antibodies. See: receptor. Synonym: Ehrlich's postulate. (05 Mar 2000) |
| nuclear chain fibre | The shortest and most numerous type of intrafusal muscle fibre's in a neuromuscular spindle, containing a single row of centrally positioned nuclei. (05 Mar 2000) |
| delta chain | See: immunoglobulin. The heavy chains of mouse and human IgD immunoglobulins. (18 Nov 1997) |
| immunoglobulins, alpha-chain | Heavy chains found in the fab and fc fragments of IgA and having a molecular weight of approximately 58 kD. They contain about 470 amino acid residues arranged in four domains and an oligosaccharide component bound covalently to the fc fragment. (12 Dec 1998) |
| immunoglobulins, delta-chain | Heavy chains found in the fab and fc fragments of IgD and having a molecular weight of approximately 64 kD. They contain about 500 amino acid residues arranged in four domains and an oligosaccharide component covalently bound to the fc fragment. (12 Dec 1998) |