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Stabilization of hydrolytically labile iron(II)–cysteine peptide thiolate complexes in aqueous triton X‐100 micelle solution: Spectroscopic properties mimicking of reduced rubredoxin
Author(s) -
Sun WeiYin,
Ueyama Norikazu,
Nakamura Akira
Publication year - 1998
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/(sici)1097-0282(199807)46:1<1::aid-bip1>3.0.co;2-r
Subject(s) - chemistry , micelle , aqueous solution , rubredoxin , cysteine , proton nmr , triton x 100 , crystallography , stereochemistry , medicinal chemistry , organic chemistry , pulmonary surfactant , enzyme , biochemistry
The absorption, CD, and 1 H‐ and 19 F‐nmr spectroscopic features of Fe(II) complexes with a series of cysteine‐containing oligopeptides were investigated in aqueous (H 2 O or D 2 O) 10% Triton X‐100 micelle solution. The complexes with distal aromatic rings, [Fe(Z‐cys‐Pro‐Leu‐cys‐Gly‐X) 2 ] 2− (Z = benzyloxycarbonyl; X = NH‐C 6 H 4 ‐ p ‐F, NH‐CH 2 ‐CH 2 ‐C 6 H 4 ‐ p ‐F, and Phe‐OMe), were found to be quite stable in such aqueous micelle solution. The coordination of cysteine–peptide ligands to the Fe(II) ion is revealed by isotropically shifted 1 H‐nmr signals due to the Cys C β H 2 protons occurring at 120 ∼ 250 ppm in a D 2 O Triton X‐100 micelle solution (10%) at 60°C that are very similar to those reported for native reduced rubredoxin. The high stability of these cysteine peptide–Fe(II) complexes in aqueous micellar system was explained by the combined contributions from NH—S hydrogen bonds and the effect of the proximity of aromatic groups. The existence of such NH—S hydrogen bonds and interactions between aromatic ring and sulfur atom was confirmed by 19 F‐nmr spectral and 19 F spin–lattice relaxation times ( T 1 ) measurements. © 1998 John Wiley & Sons, Inc. Biopoly 46: 1–10, 1998