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Absorption and circular dichroism spectra of CuCl 2 complexed with poly(S‐carboxymethyl‐ L ‐cysteine) and poly(S‐carboxyethyl‐ L ‐cysteine)
Author(s) -
Maeda Hiroshi,
Oka Kazuki,
Ikeda Shoichi
Publication year - 1985
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360240702
Subject(s) - chemistry , circular dichroism , cysteine , absorption (acoustics) , absorption spectroscopy , crystallography , stereochemistry , organic chemistry , enzyme , physics , quantum mechanics , acoustics
The interaction of CuCl 2 with poly(S‐carboxymethyl‐ L ‐cysteine) (poly[Cys(CH 2 COOH)]) and poly(S‐carboxyethyl‐ L ‐cysteine) (poly[Cys(C 2 H 4 COOH)]) were studied by absorption spectra and circular dichroism (CD). On mixing CuCl 2 with polypeptide solutions, absorption bands appeared at 320–325 nm in both polypeptides, and at 255–260 nm in the case of poly[Cys(CH 2 COOH)]. A stable bound species was formed in the case of poly[Cys(CH 2 COOH)], since the apparent molar absorption coefficient of the bound species did not depend on the mixing ratio. From the absorption data, it was inferred that Cu 2+ ions were complexed with the side chains, most probably with sulfur atoms and carboxyl groups. Induced optical activities were observed for the two polypeptides. The CD spectra of poly[Cys(CH 2 COOH)] + CuCl 2 gave simpler aspects than those of poly[Cys(C 2 H 4 COOH)] + CuCl 2 .