Tris(3, 5-Dibromosalicyl) Tricarballylate Crosslinked Hemoglobin: Functional Evaluation

Both oxy and deoxy human hemoglobin A were crosslinked with tris(3,5-dibromosalicyl) tricarballylate. The major species from both reactions contained an inter-subunit crosslink. The denaturation transition (Tm) of the oxy crosslinked hemoglobin increased 14.5 degrees C and that of deoxy crosslinked hemoglobin, 13.0 degrees C. The apparent rate constant (kapp) of autoxidation for oxy crosslinked hemoglobin remained the same as native hemoglobin but that of the deoxy crosslinked hemoglobin increased by 34%. The higher oxygen affinity and lower cooperativity of the crosslinked proteins compared with native hemoglobin indicated that the crosslink shifted the conformation to the R state.