A double mutant of sperm whale myoglobin mimics the structure and function of elephant myoglobin

X. Zhao, K. Vyas, B. D. Nguyen, Krishna Rajarathnam, G. N. La Mar, T. Li, G. N. Phillips, R. F. Eich, J. S. Olson, J. Ling, D. F. Bocian

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Abstract

The functional, spectral, and structural properties of elephant myoglobin and the L29F/H64Q mutant of sperm whale myoglobin have been compared in detail by conventional kinetic techniques, infrared and resonance Raman spectroscopy, 1H NMR, and x-ray crystallography. There is a striking correspondence between the properties of the naturally occurring elephant protein and those of the sperm whale double mutant, both of which are quite distinct from those of native sperm whale myoglobin and the single H64Q mutant. These results and the recent crystal structure determination by Bisig et al. (Bisig, D. A., Di Iorio, E. E., Diederichs, K., Winterhalter, K. H., and Piontek, K. (1995) J. Biol. Chem. 270, 20754-20762) confirm that a Phe residue is present at position 29 (B10) in elephant myoglobin, and not a Leu residue as is reported in the published amino acid sequence. The single Gln64(E7) substitution lowers oxygen affinity ~5-fold and increases the rate of autooxidation 3-fold. These unfavorable effects are reversed by the Phe29(B10) replacement in both elephant myoglobin and the sperm whale double mutant. The latter, genetically engineered protein was originally constructed to be a blood substitute prototype with moderately low O2 affinity, large rate constants, and increased resistance to autooxidation. Thus, the same distal pocket combination that we designed rationally on the basis of proposed mechanisms for ligand binding and autooxidation is also found in nature.

Original languageEnglish (US)
Pages (from-to)20763-20774
Number of pages12
JournalJournal of Biological Chemistry
Volume270
Issue number35
DOIs
StatePublished - 1995
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

Cite this

Zhao, X., Vyas, K., Nguyen, B. D., Rajarathnam, K., La Mar, G. N., Li, T., Phillips, G. N., Eich, R. F., Olson, J. S., Ling, J., & Bocian, D. F. (1995). A double mutant of sperm whale myoglobin mimics the structure and function of elephant myoglobin. Journal of Biological Chemistry, 270(35), 20763-20774. https://doi.org/10.1074/jbc.270.35.20763