Amino acid composition and thermal stability of proteins

Abstract This study investigates the relationship between the thermal stability of a globular protein and its amino acid composition. The method deals with the relationship between the amino acid compositions and melting points in a set of proteins by computing single-residue and group correlations. Groups of residues are shown to stabilize or destabilize the molecule against temperature. The stabilizing group consists of polar-charged residues and nonpolar residues possessing high surrounding hydrophobicity. The polar-uncharged residues destabilize the molecule against temperature, serine being the most destabilizing residue. A very high cooperativity exists among the stabilizing nonpolar residues suggesting that their characteristic clustering inside the globule may enhance the thermostability of a protein. In small globular proteins which act as single cooperative units, the melting temperature remains mainly a function of amino acid composition, whereas in complex molecules it depends on other factors also.