Highly purified preparations of iV-l-(S’-phosphoribosyl)adenosine triphosphate:pyrophosphate phosphoribosyltransferase from Salmonella fyphimurium have been obtained. The phosphoribosyltransferase is the first enzyme unique to histidine biosynthesis and is sensitive to feedback inhibition by histidine. The procedure used for purification preserved the histidine sensitivity of the enzyme. A mole...

Mutants of Bacillus subtilis deficient in urocanase or in imidazolonepropionate hydrolase were isolated. These mutants are unable to use L-histidine as source of carbon or nitrogen for growth. The enzymes are thus essential for the metabolism of histidine. The structural genes specifying these enzymes are closely linked to those specifying the other two enzymes essential for histidine degradati...

The effects of histidine residue placement in a de novo-designed four-alpha-helix bundle are investigated by placement of histidine residues at coiled coil heptad a positions in two distinct heptads and at each position within a single heptad repeat of our prototype heme protein maquette, [H10H24]2 [[Ac-CGGGELWKL x HEELLKK x FEELLKL x HEERLKK x L-CONH2]2]2 composed of a generic (alpha-SS-alpha)...

in this study, the effects of separate and combined intraperitoneal (ip) injections of histidine and dexamethasone were investigated on local inflammation in rats. local inflammation was induced by subcutaneous (sc) injection of histamine (100 μl, 0.1%) in ventral surface of right hind paw. the thickness of paw was measured at 30 min before and 30, 60, 90, 120, 150 and 180 min after injection o...

Two or possibly three equivalents of N-bromoacetylacetazolamide interact with two histidine residues located in the active site region of human carbonic anhydrase B. The most rapid reaction occurs at the l-nitrogen of a histidine residue and this is followed by a slower alkylation of the 3-nitrogen of the same histidine and the 3-nitrogen of a second histidine. From a reaction mixture of N-brom...

the stability constants of species present in the systems ni(ii)-pyridoxamine(pym)(a) and ni(ii)-pyridoxamine(pym)(a)-imidazole containing ligands(b) [b = imidazole(him),  benzimidazole(bim), histamine(hist) and l-histidine(his)] have been determined ph-metrically using the miniquad computer program. the existence of the species niah, nia and nia2 was proven for the ni(ii)-pym(a) system, wherea...

Inbred weanling rats were maintained on diets containing low (6%), medium (lS%), and high (40%) levels of proteins. After 45 days they were killed and the activities of histidine ammonia lyase, urocanase, and histidine pyruvate aminotransferase in liver were assayed. Histidine ammonia lyase increased with age of the rat, and the increase was proportional to the level of protein in the diet. Ani...