Gas-phase complexes of amino acids with Cu(II) and diimine ligands. Part II. Amino acids with O, N and S functional groups in the side-chain

✍ Scribed by Christine L. Gatlin; Frantiček Tureček; Tomáš Vaisar

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 889 KB
• Volume: 30
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1190301115

✦ Synopsis

Abstract

Ternary complexes of amino acids, Cu(II) and diimine ligand 2,2′‐bipyridyl (bpy) are obtained in the gas phase by electrospray ionization (ESI). The amino acids are found to bind to Cu(II) by their deprotonated carboxylate groups in the gas‐phase complexes. Collisionally activated dissociations at low ion kinetic energies of the [Cu(II)(AA – H)(bpy)]^+·^ complexes show decarboxylation followed by cleavages of the amino acid side‐chains that reveal interactions with the Cu atom of the side‐chain functional groups. Hydroxy, sulfide and disulfide groups are transferred on to the Cu atom following collisional activation, but do not displace the bpy ligand. The side‐chain functional groups and the C~β~H~2~C~α~HNH~2~ fragment are found to compete for coordination to Cu(bpy)^+^ in the products. The ε‐amino group in lysine and the guanidyl group in arginine displace the bpy ligand following decarboxylation. The fragmentations of the gas‐phase [Cu(II)(AA – H)(bpy)]^+·^ complexes are highly specific for the amino acid residues. Arginine and lysine also form doubly charged ions by ESI that distinguish lysine from the isobaric glutamine.