Accessibility of epsilon-amino groups of lysine to guanidination in kappa-elastin from bovine ligamentum nuchae.

Kappa-Elastin contains 3.81 lysyl residues per 1000 residues of amino acids. Among these residues, free epsilon-amino groups represent about 16 p. 100, as revealed by guanidination, the buried lysyl residues (buried epsilon-amino groups) represent about 33 p. 100, as revealed by dansylation. After drastic reduction by borohydride, no aldimine bonds were detected and only 6 p. 100 of "deeply buried" amino groups of lysyl residues were detected by a second dansylation. The remaining lysines (about 46 p. 100) are engaged or inaccessible.