An examination of in vivo polysome-bound activity indicates that soybean (Glycine max, cv. Prize) seed urease is synthesized on large polysomes (n >/= 15). In vitro urease synthesis is directed by a large RNA (3,000-3,300 nucleotides). Urease synthesis occurs throughout the normal protein biosynthetic phase of the developing seed. Surprisingly, the activity/antigen ratios of urease increase thr...

1. Crystalline urease is not inactivated by trypsin in the absence of a gum. In fact, the presence of trypsin alone in aqueous solutions of urease has an action similar to that of gum, that is, it acts as a "protective colloid" for urease. 2. Crystalline urease is inactivated by trypsin in the presence of a gum. This occurs with great rapidity if purified (crystalline) trypsin is used. 3. If tr...

Helicobacter hepaticus is a pathogen of rodents, which causes diverse enteric and hepatic inflammatory diseases and malignancies. The urease enzyme is an important colonization factor of gastric Helicobacter species like Helicobacter pylori, but little is known about the role and regulation of urease in enterohepatic Helicobacter species. Here it is reported that urease activity of H. hepaticus...

Urease activity was detected in the hemolymph of the silkworm, Bombyx mori from the beginning of spinning to the pharate adult stage if the larvae were reared on mulberry leaves throughout the 5th-instar (the last larval instar). In contrast, no urease activity was detected in the hemolymph of insects fed artificial diets, resulting in accumulation of urea during the spinning stage. To identify...

Effect of vitamin A compounds on the covalent binding of benzo(a)pyrene [B(a)P] to subnuclear components was studied using rat liver nuclei in vitro. The retinol-induced inhibition of the covalent binding of B(a)P depended both on the dose and the time of addition. Retinal and retinyl acetate were both potent inhibitors, but retinoic acid was less effective. Retinol induced marked inhibition of...

A series of studies were conducted to explore the inductive potential of different fibric acid derivatives on the two alternative metabolic activation pathways of 2-phenylpropionic acid (2-PPA) (a model substrate for profen drugs), namely acyl-CoA formation and acyl glucuronidation, in vivo in rats, and to evaluate whether such treatment could potentially modulate the covalent binding of profen...

The metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), the most abundant compound of the aminoimidazoazaarens (AIA) group of mutagens/carcinogens isolated from the crust of fried and broiled meat, was examined in freshly isolated hepatocytes from untreated rat, mouse, hamster, and guinea pig. Activation was evaluated by the total level of covalent binding of PhIP to macromole...

The DNA photoaffinity ligands, 7-azidoactinomycin D and 8-azidoethidium, form DNA adducts that cause chain cleavage upon treatment with piperidine. Chemical DNA sequencing techniques were used to detect covalent binding. The relative preferences for modifications of all possible sites defined by a base pair step (e.g. GC) were determined within all quartet contexts such as (IGCJ). These prefere...

(3S)-(+)-(5-Chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one) (MaxiPost, BMS-204352) is a potent and specific opener for maxi-K channels and has potential to prevent and treat ischemic stroke. Following single intravenous doses of [14C]BMS-204352 to rats, only 10 to 12% of radioactivity was extractable from plasma with organic solvents. The unextractable radioact...