Kinetic properties of erythrocyte phosphofructokinase in patients with type VII glycogenosis from two families--close similarity to liver type phosphofructokinase.

Abstract

The kinetic properties of phosphofructokinases (PFKs) from normal human liver, muscle and erythrocytes, and from erythrocytes of two unrelated patients with type VII glycogenosis (muscle PFK deficiency, McKusick 23280) were analysed in this study. Sensitivity to inhibition by ATP and to inhibition by 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate and citrate were quite different for muscle and liver PFKs. The kinetic characteristics of normal erythrocyte PFK were intermediate between those of muscle and liver PFKs. The kinetic constants of erythrocyte PFK of a patient in one family were indistinguishable from those in the other family. In addition, kinetic behaviour of residual PFK activity in erythrocytes from patients in the two families were quite similar to those of normal liver PFK. These results of kinetic analyses provide convincing evidence for the concept that normal erythrocyte PFK consists of muscle and liver type subunits. Residual erythrocyte PFK activity in type VII glycogenosis is thus concluded to reflect the activity of liver type PFK existing in patient's erythrocytes.