Deuterium relaxation and proton nuclear Overhauser effect studies of the dynamic and structural properties of hemoproteins
The flexibility of proteins is recognized as being important to their biological function, and the dynamics of heme proteins has received much attention. The application of NMR relaxation studies to heme proteins is complicated by the paramagnetism of the iron in several iron spin states. The authors have carried out a program of motional analysis of several NMR relaxation experiments, and have drawn quantitative conclusions about the internal dynamics of protein side chains in heme proteins. Deuterium NMR linewidth data from rotationally immobile deuteron labelled on the heme in myoglobin yielded protein tumbling rates in good agreement with other techniques. The linewidth of deuterated heme methyls were shown to yield the protein tumbling rate for the enzyme Horseradish Peroxidase, when used in conjunction with a spin-lattice relaxation measurement. The truncated Nuclear Overhauser Effect was shown to be an effective experiment in paramagnetic metcyano myoglobin where the cross relaxation was observed between vinyl protons; this relaxation rate was analyzed in terms of vinyl mobility, and demonstrated substantial vinyl mobility on either side of the heme plane. Deuterium NMR experiments were carried out on the alpha labelled deuterons of the 2 and 4 heme vinyl groups in myoglobin and Horseradish Peroxidase. The vinyls of Horseradish Peroxidase were found to exhibit reduced but measurable mobility, which differed substantially between the two vinyl groups. The hydrogen bond between the 7-propionic group and FG2 His in myoglobin was found to be maintained in solution. Deuterium NMR studies of heme methyl groups were used to make resonance assignments in previously unaccessible regions.
- Research Organization:
- California Univ., Davis (USA)
- OSTI ID:
- 6720063
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
CARBOXYLIC ACIDS
DEUTERIUM
DEUTERON PROBES
ENZYMES
GLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MYOGLOBIN
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OVERHAUSER EFFECT
OXIDOREDUCTASES
PEROXIDASES
PIGMENTS
PORPHYRINS
PROBES
PROTEINS
RELAXATION
RESONANCE
SPIN-SPIN RELAXATION
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS