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The structural isomerisation of human-muscle adenylate kinase as studied by 1H-nuclear magnetic resonance

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Kalbitzer,  Hans Robert
Emeritus Group Biophysics, Max Planck Institute for Medical Research, Max Planck Society;

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Marquetant-Strasser,  Rainer
Max Planck Institute for Medical Research, Max Planck Society;

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Rösch,  Paul
Emeritus Group Biophysics, Max Planck Institute for Medical Research, Max Planck Society;

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Schirmer,  R. Heiner
Max Planck Institute for Medical Research, Max Planck Society;

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Citation

Kalbitzer, H. R., Marquetant-Strasser, R., Rösch, P., & Schirmer, R. H. (1982). The structural isomerisation of human-muscle adenylate kinase as studied by 1H-nuclear magnetic resonance. European Journal of Biochemistry, 126(3), 531-536. doi:10.1111/j.1432-1033.1982.tb06813.x.


Cite as: http://hdl.handle.net/21.11116/0000-0005-1D43-0
Abstract
Human muscle adenylate kinase (ATP:AMP phosphotransferase, EC 2.7.4.3.) was studied by 1H-nuclear magnetic resonance spectroscopy. The C-2 and C-4 proton resonances of the active-center histidine His-36 could be identified; the pK of His-36 was determined as 6.1. The pK of His-189 is very low (4.9) although it is located at the surface of the protein. Other resonance lines are discussed in comparison with NMR spectra of porcine adenylate kinase [McDonald et al. (1975) J. Biol. Chem. 250, 6947-6954]. A pH-dependent structural isomerization as shown by X-ray crystallography in the pig enzyme [Pai et al. (1977) J. Mol. Biol. 114, 37-45] was not observed for human adenylate kinase in solution. However, the binding of adenosine(5')pentaphospho(5')adenosine (Ap5A), a bisubstrate inhibitor, to adenylate kinase causes an overall change of the NMR spectrum indicative of a large conformational change of the enzyme. The exchange rate (koff) for Ap5A was estimated as 10 s-1 and decreases by addition of Mg2+. On the basis of these values and the known dissociation constant it is likely that the binding of Ap5A is a diffusion-controlled process kon being 10(8) M-1 s-1. In conclusion, the system Ap5A/Mg2+/human adenylate kinase, which has been studied by NMR spectroscopy and X-ray diffraction in parallel, is suitable for analyzing the induced fit postulated by Jencks for all kinase-catalyzed reactions.