| beta-thionase | <enzyme> A multifunctional pyridoxal phosphate enzyme. In the second stage of cysteine biosynthesis it catalyses the reaction of homocysteine with serine to form cystathionine with the elimination of water. Chemical name: L-Serine hydro-lyase (adding homocysteine) Registry number: EC 4.2.1.22 (12 Dec 1998) |
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| beta-thromboglobulin | <haematology> A platelet-specific protein which is released when platelets aggregate. Elevated plasma levels have been reported after deep venous thrombosis, preeclampsia, myocardial infarction with mural thrombosis, and myeloproliferative disorders. Measurement of beta-thromboglobulin in biological fluids by radioimmunoassay is used for the diagnosis and assessment of progress of thromboembolic disorders. (12 Dec 1998) |
| beta-tocopherol | 5,8-Dimethyltocol;a lower homolog of alpha-tocopherol, that contains one less methyl group in the aromatic nucleus and is less active biologically; accompanies alpha-T and gamma-beta-tocopherol (05 Mar 2000) |
| beta-tyrosinase | <enzyme> An enzyme that catalyses the cleavage of tyrosine to phenol, pyruvate, and ammonia. It is a pyridoxal phosphate protein. The enzyme also forms pyruvate from d-tyrosine, l-cysteine, s-methyl-l-cysteine, l-serine, and d-serine, although at a slower rate. Chemical name: L-Tyrosine phenol-lyase (deaminating) Registry number: EC 4.1.99.2 (12 Dec 1998) |
| beta-ureidopropionase | <enzyme> Chemical name: n-carbamoyl-beta-alanine amidohydrolase Registry number: EC 3.5.1.6 Synonym: n-carbamoyl beta-alanine amidohydrolase (26 Jun 1999) |
| beta wave | <neurology> Brain waves in the electroencephalogram which have a frequency of 18 to 30 per second. They are typical during periods of intense activity of the nervous system, and occur principally in the parietal and frontal regions. (12 Dec 1998) |
| broad beta disease | Hyperlipoproteinaemia characterised by increased plasma levels of LDL, beta-lipoproteins, pre-beta-lipoproteins, cholesterol, phospholipids, and triglycerides; hypertriglyceridemia induced by a high carbohydrate diet, and glucose tolerance is abnormal; frequent eruptive xanthomas and atheromatosis, particularly coronary artery disease; biochemical defect lies in apolipoproteins; there are many varieties. Synonym: carbohydrate-induced hyperlipaemia, dysbetalipoproteinaemia, familial hyperbetalipoproteinaemia and hyperprebetalipoproteinaemia, familial hypercholesterolaemia with hyperlipaemia. (05 Mar 2000) |
| galactosylxylosylprotein 3-beta-galactosyltransferase | <enzyme> Catalyses the reaction of udpgalactose and 4-beta-d-(galactosyl-o-beta-d-xylosylprotein to yield udp and 3-beta-d-galactosyl-o-beta-d-xylosylprotein Registry number: EC 2.4.1.134 Synonym: galactosyltransferase II, (26 Jun 1999) |
| mannosylglycoprotein beta-1,4-N-acetylglucosaminyltransferase | <enzyme> Transfers n-acetylglucosamine from udp-glcnac in beta 1-4 linkage to the d-mannose residue of glcnac beta 1-6 (glcnac beta 1-2)man alpha-r where r is 1-6 man beta-(ch2)8cooch3 on methyl; model for asparagine linked oligosaccharide Registry number: EC 2.4.1.- Synonym: n-acetylglucosaminyltransferase vi (26 Jun 1999) |
| mannosyl-glycoprotein endo-beta-n-acetylglucosaminidase | <enzyme> A group of related enzymes responsible for the endohydrolysis of the di-n-acetylchitobiosyl unit in high-mannose-content glycopeptides and glycoproteins. Chemical name: Glycopeptide-D-mannosyl-N(4)-(N-acetyl-D-glucosaminyl)2-asparagine 1,4-N-acetyl-beta-glucosaminohydrolase Registry number: EC 3.2.1.96 (12 Dec 1998) |
| receptors, adrenergic, beta | One of the two major pharmacologically defined classes of adrenergic receptors. The alpha-beta distinction was originally based on the cellular effects of receptor activation but now relies on the relative affinities for characteristic synthetic ligands. Beta adrenergic receptors are further subdivided based on information from endogenous and cloned receptors. (12 Dec 1998) |
| receptors, adrenergic, beta-1 | A subclass of beta-adrenergic receptors (receptors, adrenergic, beta). Beta-1 adrenergic receptors are equally sensitive to epinephrine and norepinephrine and bind the agonist dobutamine and the antagonist metoprolol with high affinity. They are found in the heart, juxtaglomerular cells, and in the central and peripheral nervous systems. (12 Dec 1998) |
| receptors, adrenergic, beta-2 | A subclass of beta-adrenergic receptors (receptors, adrenergic, beta). Beta-2 adrenergic receptors are more sensitive to epinephrine than to norepinephrine and have a high affinity for the agonist terbutaline. They are widespread, with clinically important roles in skeletal muscle, liver, and vascular, bronchial, gastrointestinal, and genitourinary smooth muscle. (12 Dec 1998) |
| receptors, transforming growth factor beta | Cell-surface proteins that bind transforming growth factor beta and trigger changes influencing the behaviour of cells. Two types of transforming growth factor receptors have been recognised. They differ in affinity for different members of the transforming growth factor beta family and in cellular mechanisms of action. Transforming growth factor alpha binds to the same receptors as epidermal growth factor (see receptors, epidermal growth factor-urogastrone). (12 Dec 1998) |
| carotene, beta | An antioxidant which protects cells against oxidation damage that can lead to cancer. Beta-carotene is converted, as needed, to vitamin A. Food sources of beta carotene include vegetables such as carrots, sweet potatoes, spinach and other leafy green vegetables; and fruit such as cantaloupes and apricots. Excessive carotene in the diet can temporarily yellow the skin, a condition called carotenaemia, commonly seen in infants fed largely mushed carrots. (12 Dec 1998) |