Arginine

<p>Arginine is the <a href="/facts/Amino_acid/WDxYwBny">amino acid</a> with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H.  The molecule features a <a href="/facts/Guanidinium/lGzDoPuJ">guanidino</a> group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the l-arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of <a href="/facts/Protein/Jxmagu3E">proteins</a>. It is <a href="/facts/Genetic_code/zUK0bY1B">encoded</a> by the <a href="/facts/DNA_codon_table/9ceoWs0X">codons</a> CGU, CGC, CGA, CGG, AGA, and AGG. The guanidine group in arginine is the <a href="/facts/Precursor_(chemistry)/dUw8Mx2Y">precursor</a> for the biosynthesis of <a href="/facts/Nitric_oxide/UvhdvDzp">nitric oxide</a>. Like all amino acids, it is a white, water-soluble solid.
</p><p>The one-letter symbol R was assigned to arginine for its phonetic similarity.
</p>

Arginine open-in-new

Arginine