부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.bbabio.2005.01.008 Byline: Stefano Iotti (a), Chiara Frassineti (b), Antonio Sabatini (c), Alberto Vacca (c), Bruno Barbiroli (a) Keywords: [DELTA]G ATP hydrolysis; Creatine kinase reaction; Magnesium;.sup.31P MRS; In vivo magnetic resonance spectroscopy; Apparent equilibrium constant Abstract: Magnetic Resonance Spectroscopy affords the possibility of assessing in vivo the thermodynamic status of living tissues. The main thermodynamic variables relevant for the knowledge of the health of living tissues are: [DELTA]G of ATP hydrolysis and cytosolic [ADP], the latter as calculated from the apparent equilibrium constant of the creatine kinase reaction. In this study we assessed the stoichiometric equilibrium constant of the creatine kinase reaction by in vitro.sup.31P NMR measurements and computer calculations resulting to be: logK.sub.CK=8.00[+ or -]0.07 at T=310 K and ionic strength I=0.25 M. This value refers to the equilibrium: PCr.sup.2-+ADP.sup.3-+H.sup.+=Cr+ATP.sup.4- We also assessed by computer calculation the stoichiometric equilibrium constant of ATP hydrolysis obtaining the value: logK.sub.ATP-hyd=-12.45 at T=310 K and ionic strength I=0.25 M, which refers to the equilibrium: ATP.sup.4-+H.sub.2O=ADP.sup.3-+PO.sub.4.sup.3-+2H.sup.+ Finally, we formulated novel quantitative mathematical expressions of [DELTA]G of ATP hydrolysis and of the apparent equilibrium constant of the creatine kinase reaction as a function of total [PCr], pH and pMg, all quantities measurable by in vivo.sup.31P MRS. Our novel mathematical expressions allow the in vivo assessment of cytosolic [ADP] and [DELTA]G of ATP hydrolysis in the human brain and skeletal muscle taking into account pH and pMg changes occurring in living tissues both in physiological and pathological conditions. Author Affiliation: (a) Biochimica Clinica, Dipartimento di Medicina Clinica e Biotecnologia Applicata "D. Campanacci", Universita di Bologna, Via Massarenti, 9, 40138 Bologna, Italy (b) Dipartimento di Scienze Biomediche, Universita di Modena, via Campi 287, 41100 Modena, Italy (c) Dipartimento di Chimica, Universita di Firenze, I-50019 Sesto Fiorentino, Italy Article History: Received 3 November 2004; Revised 20 January 2005; Accepted 21 January 2005