Lysine vs. Arginine — What's the Difference?

Lysine (symbol Lys or K) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain lysyl ((CH2)4NH2), classifying it as a basic, charged (at physiological pH), aliphatic amino acid.

Arginine, also known as l-arginine (symbol Arg or R), is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, and a side chain consisting of a 3-carbon aliphatic straight chain ending in a guanidino group.

An essential amino acid, C6H14N2O2, obtained by the hydrolysis of proteins and required by the body for optimum growth.

An amino acid, C6H14N4O2, obtained from the hydrolysis or digestion of plant and animal protein.

(amino acid) An essential amino acid, C₆H₁₄N₂O₂.

An amino acid found in animal foods that plays an important role in several physiological processes.

An essential amino acid found in proteins; occurs especially in gelatin and casein

A bitter tasting amino acid found in proteins and necessary for nutrition; its absence from the diet leads to a reduced production of spermatozoa