Comparison of the Properties of Human Hemoglobin Covalently Bound to Carboxyl Dextrans with Free and Polymerized Hemoglobin

Human stroma-free hemoglobin (SFH) was coupled in the oxy or deoxy conformations to carboxyldextrans through amide bonds. The complexes were analysed by gel permeation high performance chromatography, and their molecular mass distribution ranged from 90,000 to 300,000. Covalent coupling of SFH to carboxyldextrans determined an increase of the oxygen affinity when compared to free SFH. The P. of the complex formed from carboxyldextrans and SFH in the oxy state was lower than that of the derivative obtained from SFH in the reduced state. On the other hand, glutaraldehyde cross-linked SFH still showed cooperativity when reacted in the deoxy state and in the presence of pyridoxal phosphate, and its oxygen affinity was similar to that of the free pyridoxylated SFH. These results lead to exclude the potential use of these dextran-SFH complexes as oxygen carriers.