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Spectroscopic and kinetic aspects of Elephas maximus hemoglobin
Article first published online: 3 MAR 2005
DOI: 10.1111/j.1432-1033.1990.tb15475.x
1742-4658/asset/cover.gif?v=1&s=fc98a9fc84ccc5e1b83463cabb40f397544364eb "European Journal of Biochemistry")
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How to Cite
STEPHANOS, J. J. and ADDISON, A. W. (1990), Spectroscopic and kinetic aspects of Elephas maximus hemoglobin. European Journal of Biochemistry, 189: 185–191. doi: 10.1111/j.1432-1033.1990.tb15475.x
Publication History
- Issue published online: 3 MAR 2005
- Article first published online: 3 MAR 2005
- (Received August 15/December 6, 1989) – EJB 89 1016
- Abstract
- Article
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- Cited By
In comparison with myoglobin and human and Glycera dibranchiata hemoglobins, the heme distal side amino acid exchanges within the heme environment of elephant tetrameric hemoglobin (Hbe) only slightly affect the electronic and ESR spectra of Hbe(III) and Hbe(II) derivatives, several of which were prepared and characterized by optical and ESR spectroscopy. Addition of 2,3-bisphosphoglycerate [Gri(2,3)P2] or inositol hexakisphosphate to Hbe(II)NO causes tension in the Fe-N(proximal His) bond, although the behaviour differs in detail from that of HbA(II)NO. There are two equilibrium states of Hbe having significantly different kinetics for the Hbe(III) Hbe(II) reaction of Hbe(III)NO. This autoreduction occurs in the form of two parallel processes, which collapse into one intermediate rate in the presence of Gri(2,3)P2. The temperature dependences of the rates enable deduction of H0 and S0 for the linked equilibrium, and yield liner Eyring plots for Hbe(III)NO, from which activation parameters were estimated on the basis of a previously described mechanism.