Resonance Raman spectroscopy, transient absorption, and fluorescence techniques have been employed to investigate the structure and dynamics of the α-cross-linked hemoglobin derivative, HbXL99α. The resonance Raman spectra of the deoxy form of HbXL99α are identical to those of native NbA (ν(Fe-His) ~ 222 cm-1), which exhibit a T-state (low affinity) structure regardless of solvent conditions. The resonance Raman spectra of the transient heme photoproduct resulting from CO photolysis from HbXL99α appear to have structures intermediate between deoxy-T and ligand-bound R structures (ν(Fe-His) ~ 222 cm-1). Time-resolved resonance Raman data of HbXL99α-CO show that complete CO recombination occurs after ~ 5 ms, with only a small amount of the CO-bound species reforming within ~ 200 ns (geminate recombination). Transient absorption spectra of HbXL99α-O2 indicate that the extent of sub-nanosecond geminate recombination of O2 is also reduced in the cross-linked derivative relative to native HbA. The decrease in tryptophan fluorescence of HbXL99α upon oxygenation further indicates that tertiary structural changes at the α1-β2 interface upon ligation are apparently reduced, but not eliminated in the cross-linked derivative relative to HbA.
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology
Dynamics and reactivity of HbXL99α. A cross-linked hemoglobin derivative. / Larsen, R. W.; Chavez, M. D.; Ondrias, M. R.; Courtney, S. H.; Friedman, J. M.; Lin, M. J.; Hirsch, R. E.In: Journal of Biological Chemistry, Vol. 265, No. 8, 30.03.1990, p. 4449-4454.
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