ISSN:
0887-3585
Keywords:
myoglobin
;
histidine
;
hydrophobic core
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Proton nuclear magnetic resonance spectroscopy was applied to sperm whale apomyoglobin to describe the conformation adopted by the protein under native conditions. The study focused on the A-B-G-H interface, a region known to form a compact subdomain in the apoprotein (Hughson and Baldwin, Biochemistry 28:4415-4422, 1989). Two histidine residues located in this subdomain, His24 and His119, interact and are thought to play a role in the acid denaturation process (Barrick et al., J. Mol. Biol. 237:588-601, 1994). A stable double mutant at these positions (His24Va1/His119Phe sperm whale apomyoglobin) was compared with wild-type apomyoglobin. The amino acid replacements result in chemical shift perturbations near the mutations, in particular in the AB interhelical region, and in a deceleration of backbone amide hydrogen exchange in the B helix from position 27 to position 33. The double mutant data were used to expand and confirm the wild-type spectral analysis. Signals from the D helix were identified that demonstrate the formation of holoprotein-like structure. The assigned wild-type nuclear Overhauser effects, although in small number, were sufficient to construct a model of the compact subdomain of the apoprotein. This was achieved by using the structure of the holoprotein and restraining it with the geometrical information on the apoprotein in a simulated annealing procedure. The experimental restraints define a low-resolution model of the A-B-G-H interface in apomyoglobin. © 1996 Wiley-Liss, Inc.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prot.1
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