Two
isozymes of
adenylate kinase from human
Duchenne muscular dystrophy serum, one of which was an aberrant form specific to DMD patients, were separated by
Blue Sepharose CL-6B affinity chromatography. The separated aberrant form possessed a molecular weight of 98,000 +/- 1,500, whereas the normal serum
isozyme had a weight of 87,000 +/- 1,600, as determined by SDS-
polyacrylamide gel electrophoresis, gel filtration, and sedimentation equilibrium. The sedimentation coefficients were 5.8 S and 5.6 S for the aberrant form and the normal form, respectively. Both serum
isozymes are tetramers. The subunit size of the aberrant
isozyme (Mr = 24,700) was very similar to that of the normal human liver
isozyme, and the subunit size of the normal
isozyme (Mr = 21,700) was very similar to that of the normal human muscle
enzyme. The
amino acid composition of the normal serum
isozyme was similar to that of the muscle-type
enzyme, and that of the aberrant
isozyme was similar to that of the liver
enzyme, with some exceptions in both cases.