1. 2-Chloro-1-(2,4,5-trichlorophenyl)vinyl dimethyl phosphate (tetrachlorvinphos) is demethylated by mammalian liver supernatant (100000g) protein in the presence of GSH. 2. GSH acts as an acceptor of the transferred methyl group to form S-methyl glutathione. 3. The enzyme that catalyses this reaction is present in the soluble fraction of liver from mouse, rat, rabbit and pig at similar activit...

The biosynthesis of one riboflavin molecule requires one molecule of GTP and two molecules of ribulose 5-phosphate as substrates. GTP is hydrolytically opened, converted into 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione by a sequence of deamination, side chain reduction and dephosphorylation. Condensation with 3,4-dihydroxy-2-butanone 4-phosphate obtained from ribulose 5-phosphate leads to...

1. Marked differences in the duration of symptoms were observed when sublethal single doses of different dimethyl phosphate esters were injected intravenously into rats. The compounds inducing prolonged symptoms (OO-dimethyl S-ethylthioethyl phosphorothiolate, OO-dimethyl S-ethylsulphinylethyl phosphorothiolate and OO-dimethyl S-ethylsulphonylethyl phosphorothiolate) either persisted themselves...

6,7-dimethyl-8-ribityllumazine synthase (lumazine synthase) catalyzes the condensation of 5-amino-6-ribitylamino-2,4-(1H,3H)-pyrimidinedione with 3,4-dihydroxy-2-butanone 4-phosphate, affording the riboflavin precursor, 6,7-dimethyl-8-ribityllumazine. Single turnover experiments monitored by multiwavelength photometry were performed with the recombinant lumazine synthase of Bacillus subtilis. M...

The biosynthesis of riboflavin requires 1 equivalent of GTP and 2 equivalents of ribulose phosphate. The first committed reactions of the convergent pathway are catalyzed by GTP hydrolase II and 3,4-dihydroxy-2-butanone 4-phosphate synthase. The initial reaction steps afford 5-amino-6-ribitylaminopyrimidine 5'-phosphate, which needs to be dephosphorylated by a hitherto elusive hydrolase. The de...

The chemical syntheses of monoand dimethyl esters of riboflavin phosphate were accomplished by allowing riboflavin to react with the appropriate monoand dimethylchlorophosphoric acids. Riboflavin monomethyl phosphate was found to be coenzymatically active with nicotinamide adenine dinucleotide phosphate-cytochrome c aporeductase, pyridoxine (or pyridoxamine) phosphate apooxidase, and glycolate ...

The formation of methanethiol and dimethyl disulfide in the broccoli tissue homogenates following filtration and centrifugal fractionation, and their suppression by freeze-thawing was investigated. Methanethiol was formed only in the headspace of the residue but not in the filtrate or supernatant fractions like dimethyl disulfide. Freeze-thawing, however, suppressed their formation in all homog...

Diquat (2 x 10(-4)m) inhibited both aerobic and anaerobic growth of Rhodospirillum rubrum. With photosynthetic cultures, diquat affected the synthesis of bacteriochlorophyll more readily than cell mass (turbidity). Diquat retarded the synthesis of bacteriochlorophyll and some protein more readily than that of other cellular constituents such as ribonucleic acid, deoxyribonucleic acid, and cell ...

6,7-dimethyl-8-ribityllumazine synthase (lumazine synthase) catalyzes the condensation of 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione and 3,4-dihydroxy-2-butanone 4-phosphate. Presteady state kinetic experiments using the enzyme from the hyperthermophilic bacterium Aquifex aeolicus were monitored by multiwavelength photometry. An early optical transient absorbing around 330 nm is interpre...