The transient absorbance change within the first 2 mus of photolysis of COHbI (from Scapharca inaequivalvis) reported by Chiancone et al. [Chiancone, E., Elber, R., Royer, W. E., Regan, R., and Gibson, Q. H. (1993) J. Biol. Chem. 268, 5711-5718] has been studied in several mutants. Evidence is presented that this change (rts) is associated with the allosteric transition between R and T states. Two different rts spectra relate to Hb2 and Hb2CO. No rts has been observed for mutants at position 97 (normally Phe). Correlation of ligand binding and rts shows that protein function changes at or near the rates of rts, typically, 2 x 10(6) s-1 (Hb2) and 5 x 10(5) s-1 (Hb2CO). Unique values of allosteric parameters for several mutants have been obtained by combining kinetic and equilibrium data. The effect of mutation on function thus may be assigned to allostery or to a change in intrinsic heme reactivity.
An optical signal correlated with the allosteric transition in Scapharca inaequivalvis HbI. Publishing Authors By Initials
An optical signal correlated with the allosteric transition in Scapharca inaequivalvis HbI. Journal Published:
PUBLICATION TYPE: Research Support, N.I.H., Extr
Journal: Biochemistry
VOLUME: 45
Page Numbers: 15748-55
Journal Abbreviation: Biochemistry
ISSN: 1520-4995
DAY: 19
MONTH: 12
YEAR: 2006
An optical signal correlated with the allosteric transition in Scapharca inaequivalvis HbI. Information
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LANGUAGE: eng
NlmUniqueID: 370623
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Grant and Affiliation Information for An optical signal correlated with the allosteric transition in Scapharca inaequivalvis HbI.
AFFILIATION: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA. Jeffry.Nichols@worcester.edu
Country: United States
AGENCY: United States NIGMS
GRANT: GM66756
ACRONYM: GM
MEDLINETA: Biochemistry
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