J Mol Cell Cardiol 31, 857–866 (1999) Article No. mc980925, available online at http://www.idealibrary.com on Octamer-dimer Transitions of Mitochondrial Creatine Kinase in Heart Disease Sibylle Soboll 1 , Dieter Brdiczka 2 , Dietmar Jahnke 1 , Anja Schmidt 1 , Uwe Schlattner 3 , Silke Wendt 3 , Markus Wyss 4 and Theo Wallimann 3 1 Institut fu ¨r Physiologische Chemie I, Heinrich-Heine-Universita ¨t, D-40225 Du ¨sseldorf, Germany, 2 Fakulta ¨t fu ¨r Biologie, Universita ¨t Konstanz, D-78434, Konstanz, Germany, 3 Institut fu ¨r Zellbiologie, ETH Ho ¨nggerberg, HPM F42, CH-8093 Zu ¨rich, Switzerland, and 4 F. Hoffmann-La Roche Ltd., VM4 Bldg. 241/865, CH-4070 Basel, Switzerland (Received 28 August 1998, accepted in revised form 26 January 1999) S. S, D. B, D. J, A. S, U. S, S. W, M. W  T. W. Octamer- dimer Transitions of Mitochondrial Creatine Kinase in Heart Disease. Journal of Molecular and Cellular Cardiology (1999) 31, 857–866. Mitochondrial creatine kinase (Mi-CK) occurs in dimeric and octameric forms, both in vitro and in vivo. The Mi-CK octamer, however, is the predominant form in vivo and is important for various functions of the protein. In the present study we show for the first time a significant decrease of the octamer/dimer ratio in vivo, related to ischemia-induced damage, and a similar decrease of octamer stability in vitro, induced by peroxynitrite (PN) radicals. We used animal models to induce ischemia in two different ways: acute ischemia in intact heart (Langendorff perfusion) and chronic ischemia in vivo (LAD-infarction). In both models, impairment of heart function and mitochondrial energy metabolism was associated with a significant decrease of Mi-CK octamer/dimer ratios and of Mi-CK activities. These findings, together with recent data showing that the formation of PN is induced in ischemia and that Mi-CK is a prime target of peroxynitrite (PN)-induced damage, suggest that oxygen radicals generated during ischemia and reoxygenation could be an important factor for the decreased octamer stability. To test this hypothesis, we studied the effect of PN on pure Mi-CK in vitro, both on dissociation of octamers and reassociation of dimers. At 1 m PN 66% of Mi-CK octamers dissociated into dimers, whereas octamerization of PN-modified dimers was already completely inhibited at 100  PN. Our data indicate that PN-induced damage could be responsible for the octamer-dimer transition of Mi-CK in ischemia. A loss of Mi-CK octamers would impair the channeling of high energy phosphate out of mitochondria and hence heart function in general.  1999 Academic Press K W: Cardiomyopathy; Energy metabolism; Mitochondrial creatine kinase. Mi-CK is localized in the mitochondrial in- Introduction termembrane space along the cristae membranes as well as in mitochondrial contact sites (Brdiczka et al., Mitochondrial creatine kinase (Mi-CK; E.C. 2.7.3.2) is a central enzyme of energy metabolism and 1990). It has preferential access to ATP, which is generated by oxidative phosphorylation and ex- especially important for oxidative muscle like heart (for reviews see Wyss et al., 1992; Schlattner et al., ported via the adenylate translocator (mitochondrial adenine nucleotide translocase (ANT)) (Brdiczka and 1998). Impaired creatine kinase (CK) function is of significance for the development of different patho- Wallimann, 1994). The enzyme then catalyses the reversible transphosphorylation between ATP and logical states and may be also relevant for myo- cardial diseases (Hamman et al., 1995; Gross et al., creatine to ADP and phosphocreatine. Liberated ADP is preferentially re-taken up into the mitochondrial 1996; Liao et al., 1996). Please address all correspondence to: S. Soboll, Institut fu ¨ r Physiologische Chemie I, Heinrich-Heine-Universita ¨t Du ¨ sseldorf, Uni- versita ¨tsstraße 1, 40225 Du ¨sseldorf, Germany. 0022–2828/99/040857+10 $30.00/0  1999 Academic Press