A Spanish family with erythrocyte pyruvate kinase deficiency: contribution of various immunologic methods in the study of the mutant enzyme.

Erythrocyte PK deficiency was detected in a 38-year-old man from Catalonia, in Spain. His father and his three children were proven to be heterozygous for the same mutant PK variant. This variant was characterized by low immunologic specific activity, normal (or slightly increased) stability to heat and to urea; normal isoelectric point, increased K0.5 for phosphoenolpyruvate, increased inhibition by ATP and normal activation by 0.35 mM fructose 1,6-diphosphate. The mutant PK variant was antigenically identical with wild enzyme as tested against anti wild erythrocyte PK serum by double immunodiffusion and micro complement fixation. The utility and the significance of the immunologic methods to be used in the study of mutant PK variants are discussed.