Localization of Lactic Acid Dehydrogenase Activity in Serum Fractions

Abstract

Summary

1. Using the method of Wroblewski and LaDue the LDH activity in serum has been localized to 3 electrophoretic regions. In 6 control subjects approximately 48% of the LDH activity in serum was present in the α₂-globulin, 33% between the α₁-globulin and albumin and 19% in the β-globulin. 2. Three peaks corresponding approximately to those found in serum were observed in the hemolysate from human red cells. In the 2 cases of myocardial infarction in which the total LDH activity was increased the α₁ activity peak was differentially raised while in 3 cases of leukemia, although the total activity was increased in only one instance, the percentage of the total LDH activity in the α₂ peak was uniformly increased. 3. The results obtained suggest that an examination of the LDH activity in the different serum fractions may provide a more sensitive index of alterations of LDH activity than examination of the total serum concentration of the enzyme. 4. The distinguishing chemical and physical properties of the enzymes in the three peaks, in addition to the observed electrophoretic difference, remain to be studied.