Assay of ornithine transcarbamylase and carbamyl phosphate synthetase I in submitochondrial fractions of rat liver mitochondria shows they are located primarily in the mitochondrial matrix. Therefore during the urea cycle ornithine must pass from the cytoplasm, where it is formed, to the mitochondrial matrix, where it is carbamylated. The resulting citrulline must then pass from the matrix to t...

Streptococcus lactis metabolizes arginine by the arginine deiminase (ADI) pathway. Resting cells of S. lactis grown in the presence of galactose and arginine maintain a high intracellular ornithine pool in the absence of arginine and other exogenous energy sources. Addition of arginine results in a rapid release of ornithine concomitant with the uptake of arginine. Subsequent arginine metabolis...

BACKGROUND L-Ornithine is a non-protein amino acid with extensive applications in medicine and the food industry. Currently, L-ornithine production is based on microbial fermentation, and few microbes are used for producing L-ornithine owing to unsatisfactory production titer. RESULTS In this study, Corynebacterium glutamicum S9114, a high glutamate-producing strain, was developed for L-ornit...

We have studied the regulation of the expression of ornithine decarboxylase with the aid of transgenic mice harbouring either functional human ornithine decarboxylase genes or the mouse ornithine decarboxylase promoter-driven chloramphenicol acetyltransferase fusion gene in their genome. We used three different stimuli which are well known to enhance ornithine decarboxylase activity in their ap...

Under the influence of a selective irreversible inhibitor of ornithine decarboxylase (ODC), DL-alpha-difluoromethylornithine (DFMO), early hematopoiesis was enhanced. In the bone marrow, the absolute number of cells that give rise to spleen colonies in lethally irradiated mice (CFU-S), granulocytic colonies in diffusion chambers in mice (CFU-DG), and granulocyte-monocyte colonies in agar in vit...

Polyamines are essential for cell proliferation; therefore, we hypothesized that arginase I or arginase II activities, via production of ornithine for polyamine synthesis, may be limiting for proliferation of endothelial cells (EC). Bovine coronary venular EC stably transfected with a lacZ gene (lacZ-EC, control), rat arginase I cDNA (AI-EC), or mouse arginase II cDNA (AII-EC) were utilized to ...

Ornithine decarboxylase (ODC) catalyzes the first step in the polyamine biosynthetic pathway, a highly regulated pathway in which activity increases during rapid growth. Other enzymes also metabolize ornithine, and in hepatomas, rate of growth correlates with decreased activity of these other enzymes, which thus channels more ornithine to polyamine biosynthesis. Ornithine is produced from argin...

The activity of ornithine decarboxylase, the rate-controlling enzyme in polyamine biosynthesis, was determined in tissues of normal control rats and rats made diabetic with streptozotocin. In untreated diabetic rats fed ad libitum, ornithine decarboxylase activity was markedly diminished in liver, skeletal muscle, heart and thymus. Ornithine decarboxylase was not diminished in a comparable grou...

The opportunistic fungal pathogen Aspergillus fumigatus produces siderophores for uptake and storage of iron, which is essential for its virulence. The main precursor of siderophore biosynthesis (SB), ornithine, can be produced from glutamate in the mitochondria or by cytosolic hydrolysis of ornithine-derived arginine. Here, we studied the impact of mitochondrial versus cytosolic ornithine bios...