Abstract
Sickle cell hemoglobin (Hb S) treated with nitrogen mustard (bis(beta-chloroethyl)methylamine hydrochloride) gives two reaction products, one labile and one stable. After dialysis against buffer solution, the remaining stable product is found to inhibit the polymerization of deoxyhemoglobin S. High resolution proton nuclear magnetic resonance has been used to study the structure and function of this stable product and to investigate the nature of the binding sites of nitrogen mustard to the hemoglobin molecule. The NMR results suggest that the nitrogen mustard treatment of Hb S does not alter the heme environment or the subunit interfaces of the hemoglobin molecule. Moreover, the NMR spectra have also shown that the nitrogen mustard reacts with the beta2 histidines of the hemoglobin molecule and have suggested that several other surface amino acid residues of the hemoglobin molecule are also affected by the nitrogen mustard alkylation. These NMR findings are in good agreement with the data obtained from biochemical studies of nitrogen mustard-treated Hb S. The NMR spectra also indicate that nornitrogen mustard (which is also effective in inhibiting sickling) binds with the hemoglobin molecule in a manner identical with nitrogen mustard. Sulfur mustard, on the other hand, produces no observable changes in the aromatic proton resonances, which is consistent with the fact that it does not inhibit the polymerization of deoxy-Hb S.
Highlights
From the Department of Biophysics and Microbiology Pittsburgh, Pittsburgh, Pennsylvania 15260 and Department of Biochemistry, University of EUGENE F
The NMR spectra have shown that the nitrogen mustard reacts with the fl2 histidines of the hemoglobin molecule and have suggested that several other surface amino acid residues of the hemoglobin molecule are affected by the nitrogen mustard alkylation
The NMR spectra indicate that nornitrogen mustard binds with the hemoglobin molecule in a manner identical with nitrogen mustard
Summary
The NMR spectra have shown that the nitrogen mustard reacts with the fl histidines of the hemoglobin molecule and have suggested that several other surface amino acid residues of the hemoglobin molecule are affected by the nitrogen mustard alkylation. These NMR findings are in good agreement with the data obtained from biochemical studies of nitrogen mustard-treated Hb S. Hb S and a few judiciously chosen mutant hemoglobins were treated with radioactive nitrogen mustard, digested by trypsin, and the peptides mapped and counted for radioactivity [2] These results suggested that nitrogen mustard inhibits the polymerization by binding irreversibly to the PTp 1 peptide. Studies of the effects on red blood cell survival and on erythrocyte metabolic activities have shown that the nornitrogen mustard is less toxic and perhaps more suitable than nitrogen mustard for the purpose of extracorporeal therapeutic usage. A very similar compound, sulfur mustard (S(CH,CH,Cl),), does not prevent the polymerization of deoxyhemoglobin S molecules at the concentrations examined and the ‘H NMR spectra have shown that sulfur mustard-treated hemoglobin is not alkylated as judged by the aromatic proton resonances
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
