Study on heart mitochondrial creatine kinase using a cross-linking bifunctional reagent. II. The binding sites for the creatine kinase octamer on mitochondrial membranes have different properties

Beef heart mitochondria suspended in 0.25 M sucrose were treated with 0.3% glutaraldehyde (GA). The membranes were disintegrated by ultrasonication in 0.25 M KCl and precipitated by centrifugation. The relative amount of the membrane-bound mitochondrial creatine kinase (CKm) does not depend on the time course of membrane disruption. The enzyme is not removed by repeated washing of the pellet. It is concluded that this part of CKm is cross-linked to mitochondrial membranes. The maximum amount of the enzyme capable of cross-linking to the membrane with an increase in GA concentration or incubation time makes up to about 50% of the total CKm activity present in the mitochondria. It is concluded also that the CKm binding sites differ with respect to their environment.