 Alanine is an aliphatic amino acid, because the side-chain connected to the α-carbon atom is a methyl group (-CH3); alanine is the simplest α-amino acid after glycine.The methyl side-chain of alanine is non-reactive and is therefore hardly ever directly involved in protein function.Alanine is a nonessential amino acid, meaning it can be manufactured by the human body, and does not need to be obtained through the diet.