Fourier transform Raman approach to structural correlation in hemoglobin derivatives

Area of Science:

• Biophysics
• Spectroscopy
• Biochemistry

Background:

• Understanding the structural dynamics of hemoglobin (Hb) is crucial for comprehending its function.
• Previous studies utilized resonance Raman (RR) spectroscopy to investigate Hb structure.
• Fourier transform Raman (FT-R) spectroscopy offers an alternative approach for structural analysis.

Purpose of the Study:

• To investigate the structural aspects of various hemoglobin derivatives using FT-R spectroscopy.
• To analyze changes in Hb structure related to oxidation and spin states.
• To explore the utility of FT-R for monitoring structural differences in nickel-reconstituted Hb (NiHb).

Main Methods:

• Fourier transform Raman (FT-R) measurements were performed on ferrous, ferric Hb derivatives, and NiHb.
• Near-infrared (NIR) laser excitation (1064 nm) was employed.
• Spectra were analyzed in the 600-1700 cm-1 region, focusing on porphyrin ring and globin modes.

Main Results:

• FT-R spectral shifts correlated well with changes in Hb oxidation and spin states, similar to RR findings.
• Specific bands (e.g., 1654, 1459, 1003 cm-1 for deoxyHb) were assigned to globin modes.
• Oxygen binding induced conformational changes, observable as shifts in these globin-related bands.
• FT-R successfully differentiated two distinct sites within NiHb.

Conclusions:

• FT-R spectroscopy is effective for monitoring structural changes in hemoglobin related to oxidation and spin states.
• The technique provides insights into conformational alterations upon oxygen binding.
• FT-R spectroscopy can distinguish between different functional sites in modified hemoglobins like NiHb.