NATURE OF THE CROSS-LINKING OF PROTEINS BY GLUTARALDEHYDE .2. THE FORMATION OF QUATERNARY PYRIDINIUM COMPOUNDS BY THE ACTION OF GLUTARALDEHYDE ON PROTEINS AND THE IDENTIFICATION OF A 3-(2-PIPERIDYL)-PYRIDINIUM DERIVATIVE, ANABILYSINE, AS A CROSS-LINKING ENTITY

1-(5-Amino-5-carboxypentyl)pyridinium chloride (3) and 1-(5-amino-5- carboxypentyl)-3-[1-(5-amino-5-carboxypentyl)-2-piperidyl]pyridinium chloride, anabilysine (4), have been isolated from acid hydrolysates of glutaraldehyde-treated ovalbumin and their structures confirmed by synthesis. It is concluded that the strong chromophore at ca. 265 nm shown by glutaraldehyde-treated proteins is due to the formation of such quaternary pyridinium compounds and that anabilysine residues are important in the cross-linking of proteins by glutaraldehyde.