tailieunhanh - Báo cáo khoa học: New roles of flavoproteins in molecular cell biology: Blue-light active flavoproteins studied by electron paramagnetic resonance

Exploring enzymatic mechanisms at a molecular level is one of the major challenges in modern biophysics. Based on enzyme structure data, as obtained by X-ray crystallography or NMR spectroscopy, one can suggest how substrates and products bind for catalysis. | MINIREVIEW New roles of flavoproteins in molecular cell biology Blue-light active flavoproteins studied by electron paramagnetic resonance Erik Schleicher1 Robert Bittl2 and Stefan Weber1 1 Institut fur Physikalische Chemie Albert-Ludwigs-Universitat Freiburg Germany 2 Fachbereich Physik Freie Universitat Berlin Germany Keywords cryptochrome DNA repair ENDOR EPR ESR flavoprotein paramagnetic intermediates photolyase photoreceptor radical pair Correspondence S. Weber Institut fur Physikalische Chemie Albert-Ludwigs-Universitat Freiburg Albertstr. 21 79104 Freiburg Germany Fax 49 761 203 6222 Tel 49 761 203 6213 E-mail . Received 17 March 2009 accepted 9 June 2009 doi Exploring enzymatic mechanisms at a molecular level is one of the major challenges in modern biophysics. Based on enzyme structure data as obtained by X-ray crystallography or NMR spectroscopy one can suggest how substrates and products bind for catalysis. However from the 3D structure alone it is very rarely possible to identify how intermediates are formed and how they are interconverted. Molecular spectroscopy can provide such information and thus supplement our knowledge on the specific enzymatic reaction under consideration. In the case of enzymatic processes in which paramagnetic molecules play a role EPR and related methods such as electron-nuclear double resonance ENDOR are powerful techniques to unravel important details . the electronic structure or the protonation state of the intermediate s carrying the unpaired electron spin s . Here we review recent EPR ENDOR studies of blue-light active flavoproteins with emphasis on photolyases that catalyze the enzymatic repair of UV damaged DNA and on cryptochrome blue-light photoreceptors that act in several species as central components of the circadian clock. Introduction Ultraviolet light k 300 nm is known to induce the formation of covalent linkages between pairs of thymine .