L-Ornithine:2-oxoacid aminotransferase is a specific enzyme with respect to the amino group donor. Nevertheless it was found that this enzyme is inhibited by some 4-aminobutyrate analogs, 4-aminohex-5-ynoic acid and 5-amino-l,%cyclohexadienyl-carboxylic acid (gabaculine), which are currently considered to be enzyme-activated irreversible inhibitors of I-aminobutyrate:2-oxoglutarate aminotransfe...

The enzyme ornithine carbamoyltransferase (OTCase) of Moritella abyssi (OTCase(Mab)), a new, strictly psychrophilic and piezophilic bacterial species, was purified. OTCase(Mab) displays maximal activity at rather low temperatures (23 to 25 degrees C) compared to other cold-active enzymes and is much less thermoresistant than its homologues from Escherichia coli or thermophilic procaryotes. In v...

Schimke, Robert T. (National Institutes of Health, Bethesda, Md.) and Michael F. Barile. Arginine metabolism in pleuropneumonia-like organisms isolated from mammalian cell culture. J. Bacteriol. 86:195-206. 1963.-Arginine degradation is a significant metabolic process for pleuropneumonia-like organisms (PPLO; Mycoplasma) isolated from cell culture. The conversion of arginine to ornithine in PPL...

or,-Cycloserine (5 to 10 mvl), when added to isolated hepatocytes, is shown to inhibit aspartate aminotransferase predominantly in the cytosol. At low concentrations (0.1 to 0.2 mu) it selectively inhibits alanine aminotransferase. Aminooxyacetate (0.5 mu) irreversibly inhibits all transaminase activity provided the inhibitor is added prior to substrate addition. Neither cycloserine nor aminoox...

Ferrichrome is a hydroxamate-containing siderophore produced by the pathogenic fungus Aspergillus fumigatus under iron-limiting conditions. This siderophore contains N(5)-hydroxylated l-ornithines essential for iron binding. A. fumigatus siderophore A (Af SidA) catalyzes the flavin- and NADPH-dependent hydroxylation of l-ornithine in ferrichrome biosynthesis. Af SidA was recombinantly expressed...

Background: Ornithine (Orn) plays an essential role in the metabolism of plant cells through incorporation in polyamines biosynthesis, the urea cycle and nitrogen metabolism. Physiological response of the plant cells to its two enantiomers have not been widely investigated yet.Objectives: This study aimed to evaluate effect of ornithine enantiomers on exp...

BACKGROUND A variety of stimuli cause a rapid increase in polyamine synthesis by increasing an enzyme ornithine decarboxylase required for the biosynthetic pathway of protein synthesis. Difluoromethyl ornithine is a selective inhibitor of this enzyme and hence arrests cell replication strikingly. Its effects on thyroid gland are studied with respect to change in animal's weight and levels of Tr...

PURPOSE To study the acute effects of L-ornithine hydrochloride on the function of cat retina in vivo. METHODS A small amount of ornithine was administered intravitreously or intravenously. Changes in retinal function were monitored by vitreal electroretinogram (ERG) and intraretinal ERG with K(+)-selective microelectrodes. RESULTS Intravitreal injections (0.2 to 0.5 M; 15 microliters) of o...

Rat liver ornithine decarboxylase activity was decreased by administration of putrescine (1,4-diaminobutane) or other diamines, including 1,3-diaminopropane, 1,5-diaminopentane and 1,6-diaminohexane. This effect was seen in control rats and in rats in which hepatic ornithine decarboxylase activity had been increased by administration of growth hormone (somatotropin) or thioacetamide. Loss of ac...

Topical application of retinole acid to mouse skin led to a dramatic inhibition of phorbol ester (12-O-tetradecanoylphorbol-13-acetate)-induced epidermal ornithine decarboxylase (EC 4.1.1.17) activity, an event proposed to be essen tial for tumor promotion. The degree of inhibition was de pendent on the dose and time of application of retinoic acid. In contrast, treatment with retinoic acid did...