M(2)-type pyruvate kinases (M(2)-PK) have been isolated from human leukocytes
and from the erythrocytes of a patient with erythrocyte PK hyperactivity. The kinetic characteristics
of the patient erythrocyte M(2)-PK were similar to those of leukocyte M(2)-PK except
for the Hill coefficient of phosphoenol pyruvate kinetics that showed little difference in the
values. The patient erythrocyte M(2)-PK displayed complete immunological identity with leukocyte
M(2)-PK in immunodiffusion, immunoblotting and immunoneutralization. The sensitivity
to proteolysis by trypsin and the electrophoretic migration in different conditions were
similar for the M(2)-PK of both origins. These results suggest an identity between this M(2)-PK
abnormally present in erythrocytes and the M(2)-PK from leukocytes.