| beta-carotene | An antioxidant which protects cells against oxidation damage that can lead to cancer. Beta carotene is converted, as needed, to vitamin A. A yellow carotenoid pigment that gives a reddish colour to plants such as carrots and tomatoes. It is often used as a vitamin supplement because the liver can convert it into 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) |
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| beta-carotene 15,15'-dioxygenase | <enzyme> An enzyme catalyzing the reaction of beta-carotene plus O2 producing two retinals. Synonym: beta-carotene cleavage enzyme, carotenase, carotinase. (05 Mar 2000) |
| beta-carotene cleavage enzyme | <enzyme> An enzyme catalyzing the reaction of beta-carotene plus O2 producing two retinals. Synonym: beta-carotene cleavage enzyme, carotenase, carotinase. (05 Mar 2000) |
| beta-carotene hydroxylase | <enzyme> O2-dependent NADPH-dependent monooxygenase from erwinia herbicola; forms zeaxanthin; amino acid sequence has been determined; genbank m87280 Registry number: EC 1.14.13.- Synonym: beta-carotene monooxygenase, crtz gene product (26 Jun 1999) |
| beta-chlorovinyldichloroarsine | C2H2AsCl3; dichloro(2-chlorovinyl)arsine;a war gas. It is a vesicant, a lung irritant like mustard gas, a systemic poison entering the circulation through the lungs or skin, and a mitotic poison arresting mitosis in the metaphase; dimercaprol is the antidote. Synonym: beta-chlorovinyldichloroarsine. Origin: W. Lee Lewis, U.S. Chemist 1898-1943 (05 Mar 2000) |
| beta conformation | A polypeptide chain (often a secondary structure of a protein) arranged as along zig-zag. (09 Oct 1997) |
| beta-corticotropin | Acid-or pepsin-degraded beta-corticotropin. Synonym: corticotropin. (05 Mar 2000) |
| beta-cortol | Alpha-Cortol with a 20b-OH group; the 5b enantiomer of beta-allocortol, found in urine. (05 Mar 2000) |
| beta-cortolone | Alpha-Cortolone with a 20b-OH group; the 5b enantiomer of beta-allocortolone, found in urine. (05 Mar 2000) |
| beta-cyclohexenyl carotenoid epoxidase | <enzyme> Isolated from the pepper capsicum annuum; genbank x91491 Registry number: EC 1.14.14.- Synonym: beta-chc epoxidase (26 Jun 1999) |
| beta-cyclopiazonate dehydrogenase | <enzyme> Catalyses the conversion of beta-cyclopiazonic acid to alpha-cyclopiazonic acid, forming a 5-ring fused system connecting the pyrrole and indole rings; minor descriptor (75-83); on-line and index medicus search oxidoreductases (75-83) Registry number: EC 1.3.99.9 Synonym: beta-cyclopiazonate oxidocyclase (26 Jun 1999) |
| beta-cystathionase | <enzyme> An enzyme catalyzing the hydrolysis of l-cystathionine to pyruvate, l-homocysteine, and NH3. See: cystathionine gamma-lyase. Synonym: beta-cystathionase, cystine lyase. (05 Mar 2000) |
| beta-D-fucosidase | <enzyme> Catalyses hydrolysis of terminal non-reducing beta-d-fucose residues in beta-d-fucosides; also hydrolyzes beta-d-galactosides Registry number: EC 3.2.1.38 Synonym: beta-d-fucoside fucohydrolase (26 Jun 1999) |
| beta-d-galactosidase | A sugar-splitting enzyme that catalyses the hydrolysis of lactose into d-glucose and d-galactose, and that of other beta-d-galactosides; it also catalyses galactotransferase reactions; a deficiency of beta-d -galactosidase leads to problems in the intestinal digestion of lactose; used in the production of milk products for adults who do not have the intestinal enzyme; a defect of one isozyme of beta-d-galactosidase is associated with Morquio's syndrome type B. Compare: lactase persistence, lactase restriction. Synonym: lactase. (05 Mar 2000) |
| beta-D-galactoside alpha 2-6-sialyltransferase | <enzyme> Catalyses the reaction of cmp-n-acetylneuraminate and galactosylglycoprotein to yield cmp and n-acetylneuraminylgalactosylglycoprotein; cd75 and cd75w antigen were removed as sys - it is not equivalent to the enzyme. Registry number: EC 2.4.99.1 Synonym: cmp-n-acetylneuraminate-d-galactosyl-glycoprotein n-acetylneurainyltransferase, cmp-n-acetylneuraminate-beta-galactoside alpha-2,6-sialyltransferase, beta-galactosyl(1-4)n-acetylglucosaminide alpha(2-6)-sialyltransferase, gal-glcnac(2-6)-sialyltransferase, cmp-n-acetylneuraminic acid-lactose sialytransferase, cmp-acetylneuraminate galactoside (alpha 2-6)-sialyltransferase, cmp-n-acetylneuraminate-galactosylglycoprotein sialyltransferase, alpha 2-6-sialyltransferase, cmp-sialic acid-n-acetyllactosaminide alpha (2-6)-sialyltransferase, cmp-neuac-galactoside (alpha 2-6)-sialyltransferase, gal-1-4-glcnac alpha(2-6)-sialyltransferase, siat-1, beta-galctoside alpha2,6-sialyltransferase (26 Jun 1999) |