Using non-precipitating monospecific antibodies as probes of conformation, we are studying structural differences of hemoglobins in solution. Hemoglobin Ao and A2 have been isolated, purified and carbamoylated with K14CNO. Two specific subpopulations of anti-hemoglobin antibodies have been isolated by affinity chromatogrphy using synthetic peptides correponding to alpha(129-141) and delta(5-13). The first subpopulation will be used to study conformational changes at the carboxyl terminus of the alpha chain during oxygenation based on the difference in the binding affinity between 14(C)-oxy and 14(C)-deoxy hemoglobin. Differences will be used to examine mutant and truncated hemoglobins so as to better understand the structural changes occurring during the dynamic transition from the T (deoxy) state to the R (oxy) state. The second subpopulation will be used to measure hemoglobin A2 levels in serum and in individual cells and to differentiate A2 from other normal and mutant hemoglobins. In addition we are using the labeled normal hemoglobins to quantitate the binding of hemoglobin to red cell membranes and to determine the site of this binding.