STABILITY OF A POTENTIAL BLOOD SUBSTITUTE, HBXL99-ALPHA, UNDER HIGH-PRESSURE

One important criteria for a plasma circulating hemoglobin blood subst itute is resistance to subunit dissociation. For this reason, cross-li nked hemoglobins (with low oxygen affinities) are being specifically d esigned to serve as potential blood substitutes. An example is HbXL99 alpha, cross-linked between the alpha-subunits [PNAS (1987) 84:7280]. In the study presented here, the effects of up to 2 kilobars of pressu re on the intrinsic fluorescence of HbXL99 alpha, HbA and myoglobin we re compared. Hemoglobin solutions were studied between 0.01 - 0.1g% in potassium phosphate or Hepes buffers, pH 7.4. Results show HbA exhibi ts a decrease in fluorescence intensity as a function of pressure. In contrast, HbXL99 alpha as well myoglobin (a monomer) show essentially no significant intrinsic fluorescence changes as a function of pressur e. These results suggest that HbXL99 alpha is stable as a tetramer up to similar to 2 kilobars of pressure. In addition, high pressure intri nsic fluorescence studies provide a suitable technique for determining the subunit stability of hemoglobins. (C) 1994 Academic Press Inc.