13C NMR Studies of Keratin Hydrolysate-, Polylysine-, and Polyornithine-Metal Ion Complexes.

HOSHINO Makoto, SONG Jin Cherl, YOSHIDA Takashi, URYU Toshiyuki

doi:10.1295/koron.48.341

The chemical structure of a keratin hydrolysate-Fe (II) ion complex, which is used as fire-extinguishing foam for petroleum fires, was studied by means of ¹³C NMR spectroscopy. Lower-field shift of three peaks in the ¹³C NMR spectrum of keratin hydroly-sate was observed after adding Fe (II) salt to keratin hydrolysate solution in deuterium oxide. It was assumed that the coordination of Fe (II) ion with the protein occurred at pendant amino groups of amino acid residues in the keratin hydrolysate. To analyze the structure of the protein-Fe (II) complex, poly-L-ornithine and poly-L-lysine were used as model polypeptides. Reaction of polyornithine with Fe (II) salt gave the peak broadening and lower-field shift in the ¹³C spectrum, suggesting that the coordination of Fe (II) ion to pendant amino groups of the protein might occur. The Cu (II) ion also formed a complex with poly-L-ornithine. Although no peak shift of poly-L-lysine was observed due to the addition of Fe (II) salt, the addition of Cu (II) salt to poly-L-lysine solution caused strong peak broadening at the two peaks (C^δ and C^ε). These results show that polyornitine and polylysine have an ability to form metal ion complexes. They suggest that such amino acid residues as ornithine and lysine might form a Fe (II) complex in the keratin hydrolysate fire-extinguisher.

13C NMR Studies of Keratin Hydrolysate-, Polylysine-, and Polyornithine-Metal Ion Complexes.

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