Preparative and analytical applications of immobilized haemoglobin

New applications of haemoglobin immobilized on Sepharose 4B are proposed for the removal of cell-free, potentially toxic haemoglobin from either natural biological specimens or artificial haemoglobin-containing systems (e.g., blood substitutes, haemosomes) to be employed for biomedical purposes. In a model study, an affinity column of immobilized haemoglobin was used to remove free haemoglobin from blood serum in which controlled haemolysis had been induced. The affinity column retains all the free haemoglobin, does not retain the haemoglobin-haptoglobin complex(es) and leaves the composition of the serum samples unaltered. When immobilized met-haemoglobin is used, haem is transferred readily to albumin, with which it forms a complex. This observation on the one hand shows that immobilized oxyhaemoglobin should be preferred for preparative purposes, and on the other opens the way to the characterization of the haem transfer reaction to albumin by means of immobilized met-haemoglobin. This reaction is difficult to study in solution owing to the overlap of the met-haemoglobin and methaemalbumin spectra.