Effect of glutaraldehyde on hemoglobin: functional aspects and Mössbauer parameters

Glutaraldehyde is widely used for the cross-linking of hemoglobin for blood substitute research or for technological purposes. The effects of this reagent on the biochemical properties of hemoglobin were correlated with Mössbauer data. Human hemoglobin was cross-linked by glutaraldehyde as soluble polymers and insoluble particles. Effects of cross-linking on oxygen affinity, oxidation-reduction potential, autoxidation kinetics, and thermal stability were studied. Stability of cross-linked hemoglobin was specifically studied by Mössbauer spectroscopy. Oxygen affinity is increased, redox potential is decreased, autoxidation rates are increased, and stability towards thermal denaturation is increased. The regeneration of partially denatured hemoglobin by glutaraldehyde cross-linking is shown. Effects of cross-linking on biochemical properties are explained by the hypothesis of the opening of the heme pocket on the distal-histidine side and the concomitant charge transfer from the iron to the oxygen.