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19 F NMR investigations of cobalt(II) complexes with cysteine‐containing peptide ligands
Author(s) -
Sun WeiYin,
Ueno Takafumi,
Ueyama Norikazu,
Nakamura Akira
Publication year - 1995
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260330304
Subject(s) - chemistry , cysteine , peptide , crystallography , stereochemistry , proton nmr , cobalt , residue (chemistry) , nuclear magnetic resonance spectroscopy , inorganic chemistry , enzyme , organic chemistry , biochemistry
Isotropically shifted 19 F NMR signals were observed for novel mononuclear Co(II) complexes, (Et 4 N) 2 [Co(Z‐Cys‐Pro‐Leu‐Cys‐Gly‐X) 2 ] (Z = benzyloxycarbonyl, X = NHC 6 H 4 ‐ p = F, NHC 6 H 4 ‐ m ‐F and NHCH 2 CH 2 C 6 H 4 ‐ p ‐F). Such isotropically shifted signals show very short 19 F spin‐lattice relaxation times ( T 1 ) in the range 20–150 ms compared with the corresponding SH‐free peptide ligands, Z‐Cys(SH)‐Pro‐Leu‐Cys(SH)‐Gly‐X, which revealed signals with 19 F T 1 values in the range 1600–3200 ms. The observed 19 F NMR isotropic shifts and short 19 F T 1 values in the Co(II)‐cysteine‐peptide complexes are ascribed to the formation of NH—S hydrogen bonds and the presence of interactions of aromatic groups with the sulphur atom of the coordinated cysteine residue.