/sup 17/O and /sup 14/N NMR studies of complexes of paramagnetic ions with amino acids and peptides in solution
The complexation of L-proline, glycine and L-alanine with Co/sup 2 +/ Cu/sup 2 +/ and Mn/sup 2 +/ in aqueous solution was investigated via /sup 17/O and /sup 14/N NMR. For a multiparameter least-squares fit of the paramagnetic transverse relaxation rate, 1/T/sub 2p/, the stability constants of the major monodentate and bidentate complexes were determined, some of them for the first time in this work. In addition, the /sup 17/O hyperfine coupling constant, the lifetime, enthalpy and entropy of activation for first-order ligand exchange as well as the relaxation mechanisms of the /sup 17/O nucleus in the coordination center for some complexes were also determined. The spectra of some complexes of Co/sup 2 +/ were also observed. The effect of mixed ligands on the lifetime, /sup 17/O hyperfine coupling constant, and thermodynamic parameters characterizing the first-order exchange of the bound water were also determined. With respect to the parameters of a pure aqueous complex of Co/sup 2 +/, replacement of some water molecules in the coordination center by the amino acids led to a drastic reduction of the lifetime of the remaining bound water and smaller reductions of the remaining parameters. Finally, selectively enriched sites of the dipentides, cyclo(Gly/sup */Pro), cyclo(Ala-Ala), cyclo(Pro-Pro), Boc-Ala-AlaOMeO, and Boc-Gly/sup */-ProOBz were found to bind to Co/sup 2 +/ through the peptide oxygen, offering direct evidence to this effect, proving /sup 17/O NMR to be a unique probe for studies of this nature.
- Research Organization:
- Illinois Univ., Chicago (USA)
- OSTI ID:
- 5806452
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COBALT COMPOUNDS
NMR SPECTRA
COPPER COMPOUNDS
MANGANESE COMPOUNDS
ALANINES
AMINO ACIDS
AQUEOUS SOLUTIONS
CATIONS
GLYCINE
LEAST SQUARE FIT
LIGANDS
NITROGEN 14
OXYGEN 17
PEPTIDES
PROLINE
AMINES
AZOLES
CARBOXYLIC ACIDS
CHARGED PARTICLES
DISPERSIONS
EVEN-ODD NUCLEI
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IONS
ISOTOPES
LIGHT NUCLEI
MAXIMUM-LIKELIHOOD FIT
MIXTURES
NITROGEN ISOTOPES
NUCLEI
NUMERICAL SOLUTION
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN ISOTOPES
PROTEINS
PYRROLES
PYRROLIDINES
SOLUTIONS
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS
550201* - Biochemistry- Tracer Techniques