Circular dichroic studies on Cu(II) interactions with a protamine, scylliorhinine Z3

✍ Scribed by H. Kozlowski; J. P. Aubert; M. Gusse; P. Chevaillier; M. H. Loucheux-Lefebvre

• Publisher: Wiley (John Wiley & Sons)
• Year: 1984
• Tongue: English
• Weight: 422 KB
• Volume: 23
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360230708

✦ Synopsis

The interaction of Cu(I1) with the protamine scylliorhinine 2 3 was studied by means of CD measurements. At a 1:1 molar ratio, three complexes are formed. (1) In the pH range 5-6.5, the results suggest the formation of a five-membered chelate ring through the coordination of two nitrogens atoms, the N-terminal and the contiguous peptide nitrogen. (2) At pH 2 6.4, there is involvement of the lateral NH2 group of Arg; a t pH 6.5-8, the formation of a 3N cupric complex is strongly suggested. (3) At pH 2 8, results indicate the formation of a 4N complex as a major species in Cu(II)-Z3 solution. The transformation from a 2N to a 3N complex, and from a 3N to a 4N complex was followed with the help of the a(cuNH2) -Cu(I1) charge-transfer dichroic band transitions. At Cu(II):Z3 molar ratios 2 2 and a t pH > 8, a new dichroic band appears, indicating the involvement of the tyrosine residue side chain in metal-ion complexation.