Metal complexs of poly (α-amino acids): Cu(II) chelates of acetoacetylated poly(L-lysine), poly(L-ornithine), and poly(L-diaminobutyric acid)

✍ Scribed by M. Palumbo; A. Cosani; M. Terbojevich; C. Benvegnu'; E. Peggion

• Publisher: Wiley (John Wiley & Sons)
• Year: 1978
• Tongue: English
• Weight: 567 KB
• Volume: 17
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1978.360170416

✦ Synopsis

Abstract

The cupric complexes of poly(N^ε^‐acetoacetyl‐L‐lysine), [Lys(Acac)]~n′~ poly(N^δ^‐acetoacetyl‐L‐ornithine), [Orn(Acac)]~n′~ and poly(N^γ^‐acetoacetyl‐L‐diaminobutyric acid), [A~2~bu‐(Acac)]~n~, as well as of the model compound n‐hexyl acetoacetamide, have been investigated by means of absorption, potentiometric, equilibrium dialysis, and CD measurements. While in the complex of the model compound, one chelating group is bound to one cupric ion, in the polymeric complexes two β‐ketoamide groups are bound to Cu(II) under the same experimental conditions. The binding constant of cupric ions to the three polymers and the formation constant of the Cu(II)‐__n__hexylacetoacetamide complex have been evluated. Investigation on the chiroptical properties of the three polymeric complexes shows that the peptide backbone does not undergo conformational transitions, remaining α‐helical when up to 20% of the side chains are bound to Cu(II). The optical activity of the β‐ketoamide chromophores is substantially affected by complex formation and is discussed in terms of asymmetric induction from the chiral backbone.