Purification and characterization of human sarcomeric mitochondrial creatine kinase.
In order to set the basis for detailed clinical investigations, mitochondrial creatine kinase (Mi-CK) was purified to homogeneity from human cardiac muscle. Biophysical characterization by SDS-PAGE, gel permeation chromatography and by electron microscopy of negatively stained single molecules demonstrated that, similar to other vertebrate Mi-CKs, human sarcomeric Mi-CK occurs in two different oligomeric forms, dimers and octamers, that are readily interconvertible. The apparent MTs of Mi-CK protomers, dimers and octamers were 43,600 +/- 800, 79,700 +/- 800 and 371,000 +/- 3000, respectively. In addition, isoelectric focussing proved to be a suitable technique for routinely distinguishing Mi-CK from cytosolic MM-CK and gave pl values of 8.30 +/- 0.04 and 7.44 +/- 0.04 for octameric and dimeric human sarcomeric Mi-CK. Circumstantial evidence suggests that both the highly symmetrical structure and the high pI value of Mi-CK octamers are crucial determinants for the physiological functions of this enzyme.
Walterscheid-Müller
U
U
Department of Transplant, University Hospital, Innsbruck, Austria.
Braun
S
S
Salvenmoser
W
W
Meffert
G
G
Dapunt
O
O
Gnaiger
E
E
Zierz
S
S
Margreiter
R
R
Wyss
M
M
D003402:Creatine Kinase / Q000737:chemistry* / Q000302:isolation & purification* / Q000648:ultrastructure; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D007526:Isoelectric Point; D007527:Isoenzymes; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology; D011487:Protein Conformation; D012518:Sarcomeres / Q000201:enzymology*; D017385:Sequence Homology
D007527:Isoenzymes; D003402:Creatine Kinase