Deuterium NMR study of structural and dynamic properties of horseradish peroxidase

Journal Article · Wed Apr 05 04:00:00 EDT 1989 · J. Biol. Chem.; (United States)

OSTI ID:5991511

La Mar, G N; Thanabal, V; Johnson, R D; Smith, K M; Parish, D W

High field deuterium NMR spectra have been recorded for various horseradish peroxidase complexes reconstituted with hemins possessing specific 2H labels. The line width of the 2H NMR signals of deuteroheme reconstituted-horseradish peroxidase (HRP) and its cyano complex for the immobilized skeletal 2-2H and 4-2H labels yield the overall protein rotational correlation time (22 ms at 55 degrees C), which is consistent with expectations based on molecular weight. Meso-2H4 labels yield broad (1.3 kHz) signals just upfield from the diamagnetic protein envelope for HRP, and in the central portion of the protein envelope for the CN- ligated resting state HRP. Meso-2H4-labeled mesohemin-reconstituted HRP exhibits a similar signal but shifted further upfield by approximately 10 ppm. The net upfield meso-H hyperfine shifts confirm a five-coordinate structure for resting state HRP. 2Ha resonances for essentially rotationally immobile vinyl groups were detected in both resting state HRP and CN- ligated resting state HRP. Heme methyl-2H-labeling yields relatively narrow lines (approximately 80 Hz) indicative of effective averaging of the quadrupolar relaxation by rapid methyl rotation. Thus the 2H line width of rapidly rotating methyls in hemoproteins can be used effectively to determine the overall protein tumbling rate. Preliminary 2H experiments in meso-2H4-labeled compound I do not support large pi spin density at these positions on the porphyrin cation radical, and argue for a a1u rather than a a2u orbital ground state.

• Research Organization: Univ. of California, Davis (USA)
• OSTI ID: 5991511
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 264:10; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CARBOXYLIC ACIDS
CHEMICAL SHIFT
DEUTERIUM
ENZYMES
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
PEROXIDASES
PIGMENTS
PORPHYRINS
RESONANCE
SPECTRA
STABLE ISOTOPES
TRACER TECHNIQUES