Arginine is an essential
amino acid found in proteins and is one of three amino acids categorized as basic amino
acids. The basic amino acids are strongly polar, and as a consequence,
they are usually found on the exterior surfaces of proteins, where
they can be hydrated by the surrounding aqueous environment.
Arginine is an intermediate in the urea cycle - Figure 20.14 (reactions 1-2 shown below).
Arginine is a precursor to nitric oxide. In this unusual reaction, an unprecedented five-electron oxidation of arginine occurs (reaction #3 below).
In muscle, arginine is also involved as a precursor of creatine and creatine phosphate (Reaction #4 below).
Arginine is classified as an essential amino acid in mammals, meaning it must be present in the diet.
|
One Letter Code |
Three Letter Code |
Molecular Wt. (Daltons) |
Genetic Code Codons |
|
R |
ARG |
156.20 |
CGU, CGC, CGA, CGG, AGA, AGG |
Arginine is both metabolically degraded to and synthesized from glutamate through ornithine.
1. Argininosuccinate <=> Arginine + Fumarate (catalyzed by Argininosuccinase).
2. Arginine + H2O <=> Urea + Ornithine (catalyzed by Arginase)
3. Arginine + O2 -> Citrulline + Nitric Oxide (catalyzed by Nitric Oxide Synthase).
4. Arginine + Glycine <=> Guanidinoacetate + Ornithine