A combination of dynamic light scattering and polarized resonance Raman scattering applied in the study of Arenicola Marina extracellular hemoglobin

Arenicola Marina extracellular hemoglobin (Hbl Hb) is considered to be a promising candidate as a blood substitute. To entangle some of the properties of extracellular giant hexagonal bilayer hemoglobin (Hbl Hb) of Arenicola Marina, we combined polarized resonance Raman scattering (532 nm excitation) with dynamic light scattering (DLS) (632.8 nm). An analysis of the depolarization ratio of selected a _2g skeletal modes of the heme in native Hbl Hb and porcine Hb, shows that the distortion of the heme group away from its ideal fourfold symmetry is much smaller for heme groups bound in the Hbl Hb than for heme groups bound in porcine Hb. Using DLS, the average hydrodynamic diameter ({dh}) of Hbl Hb was measured at pH = 5, 7, 8, 9, and 10. At pH = 5 to 7, the Hbl Hb was found in its native form with {dh} equal to 24.2 nm, while at pH = 8 and 9, a dissociation process starts to take place resulting in {dh} = 9 nm. At pH = 10, only large aggregates of fragmented Hbl Hb with 〈dh〉 larger than 1000 nm was detected, however, a comparison of the DLS results with the polarized resonance Raman scattering (RRS) revealed that the coupling between the fragments did not involve direct interaction between the heme groups, but also that the local heme environment seems to be comparable in the aggregates and in the native Hbl Hb. By comparing the unpolarized RRS results obtained for erythrocytes (RBC) with those for Hbl Hb, led us to the important conclusion that Hbl Hb is much easier photolyzed than porcine RBC.