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Arginine is synthesized from citrulline in the urea cycle by the sequential action of the cytosolic enzymes argininosuccinate synthetase and argininosuccinate lyase. This is an energetically costly process, because for each molecule of argininosuccinate that is synthesized, one molecule of adenosine triphosphate (ATP) is hydrolyzed to adenosine ...
Arginine synthesis also utilizes negative feedback as well as repression through a repressor encoded by the gene argR. The gene product of argR, ArgR an aporepressor, and arginine as a corepressor affect the operon of arginine biosynthesis. The degree of repression is determined by the concentrations of the repressor protein and corepressor level.
Glutamine is synthesized from NH 4 + and glutamate, and asparagine is synthesized similarly. Proline and arginine are both derived from glutamate. Serine, formed from 3-phosphoglycerate, which comes from glycolysis, is the precursor of glycine and cysteine. Tyrosine is synthesized by the hydroxylation of phenylalanine, which is an essential ...
Nitric oxide synthases produce NO by catalysing a five-electron oxidation of a guanidino nitrogen of L-arginine (L-Arg). Oxidation of L-Arg to L-citrulline occurs via two successive monooxygenation reactions producing N ω-hydroxy-L-arginine (NOHLA) as an intermediate. 2 mol of O 2 and 1.5 mol of NADPH are consumed per mole of NO formed. [3]
The transformation of citrulline into argininosuccinate is the rate-limiting step in arginine synthesis. The activity of argininosuccinate synthetase in arginine synthesis occurs largely in at the outer mitochondrial membrane of periportal liver cells as part of the urea cycle, with some activity occurring in cortical kidney cells.
Citrulline is also produced as a byproduct of the enzymatic production of nitric oxide from the amino acid arginine, catalyzed by nitric oxide synthase. In the yeast species Saccharomyces cerevisiae, citrulline is a metabolic intermediate in the latter, cytosolic half of the arginine biosynthesis pathway.
It is an amino acid derivative, naturally produced in the human body from the amino acids glycine and arginine, with an additional requirement for S-adenosyl methionine (a derivative of methionine) to catalyze the transformation of guanidinoacetate to creatine.
N-Acetylglutamic acid is the second intermediate in the arginine production pathway in Escherichia coli and is produced via NAGS. [5] In this pathway, N-acetylglutamic acid kinase (NAGK) catalyzes the phosphorylation of the gamma (third) carboxyl group of N-acetylglutamic acid using the phosphate produced by hydrolysis of adenosine triphosphate ...