Biomaterial Database

Regulation of enzymes involved in ornithine/arginine metabolism in the parasitic trypanosomatid Herpetomonas samuelpessoai. 1983

L Beutin, and H Eisen

The genetic regulation of enzymes involved in arginine and ornithine synthesis has been investigated in the parasitic trypanosomatid Herpetomonas samuelpessoai. The activities of two enzymes involved in arginine synthesis, ornithine carbamoyltransferase (OCTase) and argininosuccinate lyase (ASLase) were depressed whereas the enzyme citrulline hydrolase (CHase), which is involved in ornithine synthesis, was increased in arginine supplemented cultures of the parasites. The depression of OCTase activity in the presence of arginine was not due to feedback inhibition and CHase activity of uninduced cultures was not enhanced by exogeneous arginine. Studies of the kinetics of OCTase induction and repression revealed that arginine blocks OCTase synthesis but does not cause destruction of the enzyme. Ornithine, but not citrulline was found to counteract the arginine mediated repression of OCTase. Two classes of canavanine resistant mutants of H. samuelpessoai were isolated. One class was defective in arginine uptake whereas the other was affected in regulation of OCTase and ASLase which appear to be under coordinate control in H. samuelpessoai.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008190	Lyases	A class of enzymes that catalyze the cleavage of C-C, C-O, and C-N, and other bonds by other means than by hydrolysis or oxidation. (Enzyme Nomenclature, 1992) EC 4.	Desmolase,Desmolases,Lyase
D009952	Ornithine	An amino acid produced in the urea cycle by the splitting off of urea from arginine.	2,5-Diaminopentanoic Acid,Ornithine Dihydrochloride, (L)-Isomer,Ornithine Hydrochloride, (D)-Isomer,Ornithine Hydrochloride, (DL)-Isomer,Ornithine Hydrochloride, (L)-Isomer,Ornithine Monoacetate, (L)-Isomer,Ornithine Monohydrobromide, (L)-Isomer,Ornithine Monohydrochloride, (D)-Isomer,Ornithine Monohydrochloride, (DL)-Isomer,Ornithine Phosphate (1:1), (L)-Isomer,Ornithine Sulfate (1:1), (L)-Isomer,Ornithine, (D)-Isomer,Ornithine, (DL)-Isomer,Ornithine, (L)-Isomer,2,5 Diaminopentanoic Acid
D009954	Ornithine Carbamoyltransferase	A urea cycle enzyme that catalyzes the formation of orthophosphate and L-citrulline (CITRULLINE) from CARBAMOYL PHOSPHATE and L-ornithine (ORNITHINE). Deficiency of this enzyme may be transmitted as an X-linked trait. EC 2.1.3.3.	Ornithine Transcarbamylase,Ornithine Carbamylphosphate Transferase,Carbamoyltransferase, Ornithine,Carbamylphosphate Transferase, Ornithine,Transcarbamylase, Ornithine,Transferase, Ornithine Carbamylphosphate
D002172	Canavanine
D002956	Citrulline
D005786	Gene Expression Regulation	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.	Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D000581	Amidohydrolases	Any member of the class of enzymes that catalyze the cleavage of amide bonds and result in the addition of water to the resulting molecules.	Amidases,Amidohydrolase
D001120	Arginine	An essential amino acid that is physiologically active in the L-form.	Arginine Hydrochloride,Arginine, L-Isomer,DL-Arginine Acetate, Monohydrate,L-Arginine,Arginine, L Isomer,DL Arginine Acetate, Monohydrate,Hydrochloride, Arginine,L Arginine,L-Isomer Arginine,Monohydrate DL-Arginine Acetate
D001123	Argininosuccinate Lyase	An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease ARGININOSUCCINIC ACIDURIA in man. EC 4.3.2.1.	Argininosuccinase,Lyase, Argininosuccinate