Membrane-localized pyruvate kinase of red blood cells in hemolytic anemia associated with pyruvate kinase deficiency.

Pyruvate kinase activity of red blood cell membranes, which is normally masked, has been determined after mechanical disruption of the membranes in normal individuals and in three homozygous patients with pyruvate kinase deficiency. Although patients 1 and 2, who were siblings, had relatively high enzyme activities in their hemolysates, they had the severest form of the disorder. The activities of their membrane fragments were decreased to seven per cent of fragments of normal membranes. Patient 3 had a mild form of hemolytic anemia despite a low enzyme activity of his hemolysates. The membrane fragments of this patient contained 28 per cent of the pyruvate kinase activity of normal fragments. The data suggest a relationship between the amount of membrane-localized pyruvate kinase and the severity of the clinical disorder. The reduced production of ATP by the enzyme portion localized within the membrane may cause an impairment of membrane functions in pyruvate kinase deficiency.