arginine biosynthetic process via ornithine
Definition
Target type: biologicalprocess
The chemical reactions and pathways resulting in the formation of arginine (2-amino-5-guanidinopentanoic acid) via the intermediate compound ornithine. [GOC:jl]
Arginine biosynthesis via ornithine is a crucial metabolic pathway that produces the amino acid arginine, an essential component of proteins, and a precursor for various biomolecules. This process is tightly regulated and involves several enzymatic steps, with ornithine serving as an intermediate.
The pathway begins with the conversion of glutamate to N-acetylglutamate by N-acetylglutamate synthase. This reaction is the committed step in arginine biosynthesis and is regulated by the availability of arginine itself.
N-acetylglutamate is then used by carbamoyl phosphate synthetase I (CPS I) to produce carbamoyl phosphate. CPS I is located in the mitochondria and utilizes ATP, bicarbonate, and ammonia to synthesize carbamoyl phosphate.
Carbamoyl phosphate is then transferred to ornithine by ornithine transcarbamylase, forming citrulline. This reaction occurs in the mitochondria and is the first step in the urea cycle, where citrulline is further metabolized to urea.
Citrulline exits the mitochondria and enters the cytoplasm, where it is coupled with aspartate by argininosuccinate synthetase. This reaction utilizes ATP and generates argininosuccinate.
Finally, argininosuccinate lyase cleaves argininosuccinate to produce arginine and fumarate. Arginine is then available for protein synthesis, as a precursor for nitric oxide, or for further metabolism.
The arginine biosynthetic pathway is essential for maintaining nitrogen homeostasis and for producing crucial molecules involved in various cellular processes. Dysregulation of this pathway can lead to metabolic disorders and health problems.
The pathway is tightly regulated at multiple levels, including enzyme activity, substrate availability, and product feedback inhibition. This ensures that arginine production is balanced with cellular demand and maintains metabolic stability.'
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Proteins (1)
| Protein | Definition | Taxonomy |
|---|---|---|
| Ornithine transcarbamylase, mitochondrial | An ornithine transcarbamylase, mitochondrial that is encoded in the genome of human. [PRO:DNx, UniProtKB:P00480] | Homo sapiens (human) |
Compounds (4)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| phosphoric acid | phosphoric acid : A phosphorus oxoacid that consists of one oxo and three hydroxy groups joined covalently to a central phosphorus atom. phosphoric acid: concise etchant is 37% H3PO4 | phosphoric acids | algal metabolite; fertilizer; human metabolite; NMR chemical shift reference compound; solvent |
| diphosphoric acid | diphosphoric acid : An acyclic phosphorus acid anhydride obtained by condensation of two molecules of phosphoric acid. | acyclic phosphorus acid anhydride; phosphorus oxoacid | Escherichia coli metabolite |
| methylene diphosphonate | medronic acid : A 1,1-bis(phosphonic acid) consisting of methane substituted by two phosphonic acid groups. | 1,1-bis(phosphonic acid) | bone density conservation agent; chelator |
| n(delta)-(phosphonoacetyl)-l-ornithine |