Formation by formaldehyde of a cross-link between lysine and tyrosine residues in wool

Abstract

Wool combines irreversibly with formaldehyde at low concns. in neutral soln. at 60[degree]. It is suggested that new cross-links are formed which increase the resistance to alkaline degradation, prevent supercontraction and increase the tensile strength of the fibers. These effects are reversed by hot solns. of pH < 3 without, however, liberating the formaldehyde. The links are stable to alkali. Analytical data and the effects of formaldehyde treatment of chemically modified wools seem to indicate that formaldehyde forms cross-links between phenyl groups from tyrosine and [epsilon] -amino groups from lysine. These are broken by acid without liberation of the formaldehyde, which remains in the wool as methylol tyrosine.