| beta-n-acetylhexosaminidase | <enzyme> An enzyme hydrolyzing terminal non-reducing n-acetyl-d-hexosamine residues in n-acetyl-beta-d-hexosaminides. It acts on glucosides, galactosides, and several oligosaccharides. Hexosaminidase a cleaves gm2, ga2, globosides, and hexosamine oligosaccharides. Deficiency of this isoenzyme causes tay-sachs disease. Hexosaminidase b cleaves all the above substrates except gm2. A deficiency of both a and b causes sandhoff disease. The enzyme has also been used as a tumour marker to distinguish between malignant and benign disease. Chemical name: beta-N-Acetyl-D-hexosaminide N-acetylhexosaminohydrolase Registry number: EC 3.2.1.52 (12 Dec 1998) |
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| beta-naphthoflavone | <chemical> A polyaromatic hydrocarbon inducer of p4501a1 and p4501a2 cytochromes. (proc soc exp biol med 1994 dec:207(3):302-308) Pharmacological action: enzyme inhibitors. (12 Dec 1998) |
| beta-normal | <radiobiology> Beta-N, the normalised beta, is beta relative to the beta limit. (09 Oct 1997) |
| beta-oxidation | <biochemistry> The oxidative breakdown of fatty acids into acetyl-coenzyme A by repeated oxidation at the beta-carbon atom. Oxidation of the beta-carbon (carbon 3) of a fatty acid causes the formation of the beta-keto (beta-oxo) acid analog. This is of importance in fatty acid catabolism, the entire pathway for the catabolism of saturated fatty acids containing an even number of carbon atoms. Beta-oxidation is a part of this pathway and acetyl-CoA is a major product of this pathway. (05 Mar 2000) |
| beta-oxidation-condensation theory | <biochemistry> That the two carbon fragments split from the fatty acid molecule by beta-oxidation are converted to acetic acid and then condensed to acetoacetic acid. (05 Mar 2000) |
| beta-poloidal | <radiobiology> Beta-P is the same as the ordinary beta, except only the poloidal field is used in calculating the magnetic field pressure. Beta-P is greater than 1 in many modern tokamaks. (09 Oct 1997) |
| beta-sitosterol | Stigmast-5-en-3b-ol; (24R)-24-ethyl-5-cholesten-3b-ol;a phytosterol and anticholesteraemic. Synonym: cinchol. (05 Mar 2000) |
| beta-sulfinylpyruvic acid | <biochemistry> An intermediate product of l-cysteine catabolism in mammalian tissue. Structure: HO2S-CH2-CO-COOH (05 Mar 2000) |
| 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) |
| 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) |
| betacism | A defect in speech in which the sound of b is given to other consonants. Origin: G. Beta, the second letter of the alphabet (05 Mar 2000) |
| betacyanin | One of several red plant pigments; a betalain. An example is betanin. Elevated in urine of individuals with beeturia. Origin: L. Beta, beet, + G. Kyanos, dark blue substance, + -in (05 Mar 2000) |