Solution deuterium NMR quadrupolar relaxation study of heme mobility in myoglobin
- Univ. of California, Davis (USA)
NMR spectroscopy has been used to monitor the quadrupolar relaxation and motional dynamics of {sup 2}H selectively incorporated into skeletal and side chain positions of the heme in sperm whale myoglobin. The hyperfine shifts of the heme resonances in paramagnetic states of myoglobin allow resolution of the signals of interest, and paramagnetic contributions to the observed line widths are shown to be insignificant. The {sup 2}H line widths for the skeletal positions of deuterohemin-reconstituted myoglobin yield a correlation time identical with that of overall protein tumbling (9 ns at 30{degree}C) and hence reflect an immobile heme group. The {sup 2}H NMR line widths of heme methyl groups exhibit motional narrowing indicative of very rapid internal rotation. Hence the methyl rotation is effectively decoupled from the overall protein tumbling, and the residual quadrupolar line width can be used directly to determine the protein tumbling rate. The {sup 2}H NMR lines from heme vinyl groups were found narrower than those from the heme skeleton. However, the range of quadrupolar coupling constants for sp{sup 2} hybridized C-{sup 2}H bonds does not permit an unequivocal interpretation in terms of mobility. 48 refs., 4 figs.
- OSTI ID:
- 5092844
- Journal Information:
- Journal of the American Chemical Society; (USA), Vol. 111:2; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HEME
MOBILITY
DEUTERIUM
EXPERIMENTAL DATA
MYOGLOBIN
NMR SPECTRA
CARBOXYLIC ACIDS
DATA
GLOBINS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PORPHYRINS
PROTEINS
SPECTRA
STABLE ISOTOPES
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation