| protein structure | The amino acids and their manner of arrangement in constituting a protein. The four stages of protein structuring are primary (protein structure, primary see amino acid sequence), secondary (protein structure, secondary), tertiary (protein structure, tertiary), and quaternary (protein structure, quaternary see protein conformation). (12 Dec 1998) |
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| protein structure, secondary | The stage in the development of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices and beta sheets. This is the first folding level of protein building. (12 Dec 1998) |
| protein structure, tertiary | The stage in the structural development of a protein in which combinations of alpha helices and beta sheets pack together to form compactly folded globular units named domains. Small proteins consist of only one domain but larger proteins contain a number of domains which are usually connected by open lengths of polypeptide chain. This stage is a combination of the second and third folding levels of protein building. (12 Dec 1998) |
| protein synthesis | The process in which individual amino acids, whether of exogenous or endogenous origin, are connected to each other in peptide linkage in a specific order dictated by the sequence of nucleotides in DNA; this governing sequence is conveyed to the synthesizing apparatus in the ribosomes by mRNA, formed by base-pairing on the DNA template. (05 Mar 2000) |
| protein synthesis inhibitor | Compounds which inhibit the synthesis of proteins. They are usually antibiotics or toxins. Mechanism of the action of inhibition includes the interruption of peptide-chain elongation, the blocking the the a site of ribosomes, the misreading of the genetic code or the prevention of the attachment of oligosaccharide side chains to glycoproteins. (12 Dec 1998) |
| protein targeting | The process through which newly-made proteins are sorted and carriedto different parts of a cell. (09 Oct 1997) |
| protein Zero | <protein> The major glycoprotein of peripheral nerve myelin, an integral transmembrane protein, synthesised by Schwann cells (Mw = 28, 500). (18 Nov 1997) |
| protein-arginine n-methyltransferase | <enzyme> An enzyme that catalyses the methylation of arginine residues of proteins to yield n-mono- and n,n-dimethylarginine. This enzyme is found in many organs, primarily brain and spleen. Chemical name: S-Adenosyl-L-methionine:protein-L-arginine N-methyltransferase Registry number: EC 2.1.1.23 (12 Dec 1998) |
| protein-bound iodine | Thyroid hormone in its circulating form, consisting of one or more of the iodothyronines bound to one or more of the serum proteins. (05 Mar 2000) |
| protein-bound iodine test | A formerly used test of thyroid function in which serum protein-bound iodine is measured to provide an estimate of hormone bound to protein in peripheral blood. Synonym: PBI test. (05 Mar 2000) |
| protein-calorie malnutrition | Severe deficiency of protein + inadequate caloric intake = kwashiorkor. (12 Dec 1998) |
| protein-D-aspartate methyltransferase | <enzyme> For protein carboxymethylases consider also protein o-methyltransferase Registry number: EC 2.1.1.77 Synonym: d-aspartyl-l-isoaspartyl methyltransferase, protein d-aspartate-l-isoaspartate methyltransferase, protein l-isoaspartate o-methyltransferase, protein-beta-aspartate methyltransferase, protein-l-isoaspartate methyltransferase, protein l-isoaspartyl methyltransferase, isoaspartyl-aspartyl protein methyltransferase, protein-d-asp methyltransferase, l-isoaspartyl protein carboxymethyltransferase, pcm gene product, pcmt1 gene product (26 Jun 1999) |
| protein-energy malnutrition | The lack of sufficient energy or protein to meet the body's metabolic demands, as a result of either an inadequate dietary intake of protein, intake of poor quality dietary protein, increased demands due to disease, or increased nutrient losses. (12 Dec 1998) |
| protein-glutamine gamma-glutamyltransferase | <enzyme> An enzyme that catalyses the reaction of protein glutamine and an alkylamine to yield protein n(5)-alkylglutamine and ammonia. The gamma-carboxamide groups of peptide-bound glutamine residues act as acyl donors, and the 6-amino groups of protein- and peptide-bound lysine residues act as acceptors, to give intra- and inter-molecular n(6)-(5-glutamyl)lysine crosslinks. In the epidermis these cross-linked proteins are involved in the formation of the cornified envelope of the stratum corneum cells. In the plasma, the transglutaminase is called factor xiiia, the activated form of factor xiii. The crosslinking results in the stabilization of the fibrin clot. Pharmacological action: coagulants. Chemical name: Protein-glutamine:amine gamma-glutamyltransferase Registry number: EC 2.3.2.13 (12 Dec 1998) |
| protein-histidine kinase | <enzyme> Sass involved in transduction of starvation and cell density inputs; hkna isolated from bacillus thuringiensis; ciah isolated from streptococcus pneumoniae; do not confuse with plp1 protein Registry number: EC 2.7.3.- Synonym: histidine protein kinase, histidine kinase, hkna gene product, ciah gene product, kinc gene product, prrb gene product, plec gene product, mxcq gene product, rese gene product, hpka gene product, comd gene product, plpa gene product (phytochrome-like), divj gene product, sensor histidine kinase, sass gene product (26 Jun 1999) |