Amino Acids - Arginine R (Arg)

The Biology Project > Biochemistry > The Chemistry of Amino Acids

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Arginine R (Arg)

Chemical Properties:
    Basic
(Basic R-group) Physical Properties:
    Polar (positively charged)


Arginine, an essential amino acid, has a positively charged guanidino group. Arginine is well designed to bind the phosphate anion, and is often found in the active centers of proteins that bind phosphorylated substrates. As a cation, arginine, as well as lysine, plays a role in maintaining the overall charge balance of a protein.

Arginine also plays an important role in nitrogen metabolism. In the urea cycle, the enzyme arginase cleaves (hydrolyzes) the guanidinium group to yield urea and the L-amino acid ornithine. Ornithine is lysine with one fewer methylene groups in the side chain. L-ornithine is not normally found in proteins.

There are 6 codons in the genetic code for arginine, yet, although this large a number of codons is normally associated with a high frequency of the particular amino acid in proteins, arginine is one of the least frequent amino acids. The discrepancy between the frequency of the amino acid in proteins and the number of codons is greater for arginine than for any other amino acid.

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The Biology Project > Biochemistry > The Chemistry of Amino Acids

The Biology Project
Department of Biochemistry and Molecular Biophysics
University of Arizona
August 25, 2003
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