Question

What are the conditions for considering a group of amino acid as protein?

Answer 1

Proteins are polymers of multiple monomer units called amino acid, which have many different functional groups. More than 500 amino acids exist in nature, but the proteins in all species, from bacteria to humans, consist mainly of only 20 called the essential amino acids. The 20 major amino acids, along with hundreds of other minor amino acids, sustain our lives. Cysteine, tryptophan, and methionine are rare amino acids; together they constitute approximately 5 percent of the amino acids in a protein. Four amino acids—leucine, serine, lysine, and glutamic acid—are the most abundant amino acids, totaling 32 percent of all the amino acid residues in a typical protein.