| beta-ketoacyl-ACP reductase | A part of the fatty acid synthase complex; an enzyme reversibly reacting 3-oxoacyl-ACP with NADPH to form d-3-hydroxyacyl-ACP and NADP+. Synonym: beta-ketoacyl-ACP reductase. (05 Mar 2000) |
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| beta-ketoacyl-ACP synthase | <enzyme> An enzyme condensing malonyl-ACP and acyl-cys-protein to 3-oxoacyl-ACP + cys-protein + CO2, and similar reactions, as steps in fatty acid synthesis; cys-protein is also a part of the fatty acid synthase complex. Synonym: acyl-malonyl-ACP synthase, beta-ketoacyl-ACP synthase. (05 Mar 2000) |
| beta-ketoadipyl-coenzyme A thiolase | <enzyme> Last enzyme in the beta-ketoadipate pathway in pseudomonas putida; genbank l33795 Registry number: EC 2.3.1.- Synonym: pcaf gene product, beta-ketoadipyl-CoA thiolase (26 Jun 1999) |
| beta-ketohydrogenase | Beta-Hydroxyacyl dehydrogenase;enzyme catalyzing the oxidation of an l-3-hydroxyacyl-CoA to a 3-ketoacyl-CoA with reduction of NAD+; one of the enzymes of the b oxidation of fatty acids. Synonym: beta-ketohydrogenase, beta-ketoreductase. (05 Mar 2000) |
| beta-ketoreductase | Beta-Hydroxyacyl dehydrogenase;enzyme catalyzing the oxidation of an l-3-hydroxyacyl-CoA to a 3-ketoacyl-CoA with reduction of NAD+; one of the enzymes of the b oxidation of fatty acids. Synonym: beta-ketohydrogenase, beta-ketoreductase. (05 Mar 2000) |
| beta-ketothiolase | <enzyme> An enzyme catalyzing the thioclastic cleavage by coenzyme A of beta-ketoacyl-CoA, forming an acyl-CoA with a carbon chain shorter by two atoms, the missing two atoms appearing as acetyl-CoA. A step in fatty acid degradation. See: acetyl-CoA acetyltransferase. Synonym: 3-ketoacyl-CoA thiolase, beta-ketothiolase. (05 Mar 2000) |
| beta-lactam | <pharmacology> A class of broad spectrum antibiotics that are structurally and pharmacologically related to the penicillins and cephalosporins. (05 Mar 2000) |
| beta-lactamase | <enzyme> An enzyme produced by some bacteria, which causes the breakdown of the active form of some penicillin antibiotics, rendering them ineffective. It causes the hydrolysis of a beta-lactam (as penicillin to penicilloic acid); found in most strains of staphylococcus bacteria that are naturally resistant to penicillin. Synonym: cephalosporinase, penicillinase. (05 Mar 2000) |
| beta-lactamase inhibitor | <pharmacology> Drugs such as clavulanic acid, which are used to inhibit bacterial beta-lactamases; often used with a penicillin or cephalosporin to overcome drug resistance. (05 Mar 2000) |
| beta-lactamases | <enzyme> Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins. Chemical name: beta-Lactamhydrolase Registry number: EC 3.5.2.6 (12 Dec 1998) |
| beta-lactam resistance | Nonsusceptibility of an organism to the action of the beta-lactam antibiotics. (12 Dec 1998) |
| beta-mercaptoethanol | HO-CH2-CH2-SH;a reagent used to reduce disulfide bonds, particularly in proteins, and to prevent their formation. Synonym: beta-mercaptoethanol. (05 Mar 2000) |
| 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) |
| 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) |