Guanidination of kappa-elastin from bovine ligamentum nuchae

Kappa-Elastin is exhaustively guanidinated in order to chemically modify the pre-existing lysine content to homoarginine. However the pre-existing lysine content is only modified to homoarginine content about 50 p.cent. The other lysyl-bonds are buried or/and engaged to aldi-imine bonds or other bonds. Therefore the first guanidinated kappa-Elastin is submitted to partial acide hydrolysis (HCL, 1 N, 110 degrees C for 2 hours) and submitted to a second exhaustive guanidination. The pre-existing lysin content in kappa-Elastin almost quantitively disappeared and is transformed to the corresponding homoarginine. These results are similar to those obtained by photolysis of (Iso) desmosine residues by UV light which will liberate "new" lysine containing peptides from kappa-Elastin.