Synthesis of a Novel Acyl Phosphate Cross-linker and its Modification of Hemoglobin

Hemoglobin-based oxygen carriers (HBOCs) are of great interest for their potential as a safer alternative to blood transfusions. To overcome the vasoactivity associated with small HBOCs, our group is interested in connecting two hemoglobin tetramers together, forming “bis-tetramers”. Bis-tetramers have previously been synthesized by our group, but yield and purity of the resulting solutions have been low and hindered their usefulness for trials. A new cross-linker was designed in an attempt to improve yield. This thesis describes the synthesis of an acyl phosphate cross-linker N-[bis(sodium methyl phosphate)isophthalyl]-4-azidomethylbenzoate (5), its modification of hemoglobin and subsequent purification attempts of the resulting solution. Cross-linker 5 was found to be selective to β-β-crosslinking and produced singly modified subunits as byproducts. Attempts to purify the resulting reaction mixture by heating resulted in the decomposition of the azide group on the cross-linker, which was critical for the coupling step. Efforts to overcome this problem were unsuccessful.MAS