Studies on Human

M YOGLOBIN is a herne-prot.eiii involved in the transfer of oxygen to the muscle tissues. Its molecular weight is about one-fourth that of hemoglobin.’ It has only one heme(protoporphyrin-Fe) group attached to its protein moiety, in contrast to the four present in hemoglobin.2 tfhe protein part of myoglobin is not identical with the globin of the red cell pigment. Terminal amino group determination-which itidicates the number of polypeptide chains in a proteinreveals six such groups, furnished by valine, for horse hemoglobin.3 Horse myoglobin has only a single terminal amino-group supplied by glycine.3 The muscle pigment is, therefore, not merely a “quarter-hemoglobin”4 but a distinct protein it., its own right. It is hOWestablished that in sickle cell disease a pathologic (type S) hemoglol)in resides within the red cells.5 This abnormal pigment is responsible for the sickling phenomenon of the erythrocytes and accounts for many of the hematologic features of this disease.6 Since in sickle cell anemia severe muscular pain is frequently observed, the question arose whether an abnormal myoglobin might he present.. In the present study, purified hemoglobin-free myoglohin preparations obtained from individuals with sickle cell anemia were compared w’ith similar preparations from hematologically normal persons. Characterization of the proteins was attempted by spectroscopic and electrophoretic techni cs.