 Amino acid composition

The amino acid composition lists amounts or proportions of the different amino acid residues in a protein or specified polypeptide chain, without giving their order. The toy MAGAMG and MMAAGG each have counts M:2, A:2, G:2, or a proportion $1/3$ of each. Knowing composition therefore does not supply protein primary structure. Sanger's account begins by distinguishing the already available composition measurements from the largely unknown residue order. See Sanger's authored 1985 account of the move from composition to terminal-residue analysis.