the fragment ions and determining whether or not the fragment ions include fragment ions which are indicative of a variant of hemoglobin application_number US 201515128198 A description normal adult human hemoglobin hb exists as a non covalently assembled tetramer consisting of two alpha chains mw 15 126 4 and two beta chains 15 867 2 in which each chain is associated with a heme group mw 616 5 the average molecular weight of the intact assembly is 66 453 2 the primary function of hemoglobin is to deliver oxygen to the organs of the body structural abnormalities within the sequence of one of these chains can affect the overall function of the assembled hemoglobin tetramer in adult human hemoglobin approximately 1000 alpha and beta chain abnormalities variants have been described and many more are possible hemoglobin variants are generally caused by a single base mutation in a globin gene some variants are clinically significant whilst many function normally knowledge of how each type of change specifically alters the function is important in understanding how hemoglobin works as well as for treating diseases caused by hemoglobin variants fig1 shows a parent ion mass spectrum of native human hemoglobin showing multiply charged ions detected ranging from m 15h 15 to m 20h 20 fig2 shows.