Response of the local heme environment of (carbonmonoxy)hemoglobin to protein dehydration.

摘要: The effects of protein dehydration upon the equilibrium and dynamic properties heme active site in human hemoglobin (HbA) have been probed by resonance Raman scattering. Spectra carbonmonoxy-HbA photolytic transient species generated within 10 ns ligand photolysis obtained from thin films various stages dehydration. These data provide detailed information concerning response its bonding interactions with both proximal histidine carbon monoxide as a function hydration. For hydration levels 0.4-1.0 g H2O/g protein, our results indicate that C = O stretching mode is dramatically affected levels, thus corroborating infrared Brown et al. [Brown, W. E., Sutcliffe, J. W., & Pulsinelli, P. D. (1983) Biochemistry 22, 2914-2923]. However, we find skeletal modes Fe-C bond strength are largely insensitive to Moreover, pocket geometry (as reflected behavior Fe-proximal mode) immediately following was found be very similar R-state solution hemoglobin. At below theoretical monolayer limit, small changes spectra HbCO subsequent detected. include broadening shift lower frequency Fe-His species.(ABSTRACT TRUNCATED AT 250 WORDS)