UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

Guest
2024-11-23 17:57
 HOME     CONFERENCES     SEARCH            LOGIN     NEW USER     IMAGES   


Conference: Bucharest University Faculty of Physics 2009 Meeting


Section: Biophysics; Medical Physics


Title:
Physical characterization of GMP Kinase from Haemophilus influenzae by fluorimetric and calorimetric analysis


Authors:
Claudia Chilom (1), Razvan Gamanut (1), Andra Oprea (1), Adriana Andronie (2), Doina Gazdaru (1), Florina Toma (3), Ecaterina Feraru (3), Aurel Popescu (1)


Affiliation:
Research Centre in Molecular Biophysics1, Faculty of Physics, University of Bucharest, Romania

3 Nano SAE Research Centre2, University of Bucharest, Romania

National Institute of Research and Development for Microbiology and Immunology, Cantacuzino3, Bucharest, Romania


E-mail
claudiafir@gmail.com


Keywords:
guanosine monophosphate kinase, fluorescence, calorimetry


Abstract:
The proteins guanosine monophosphate kinases (GMPKs) are component parts of cytosolic NMP kinase family with a very important role in the activation of guanosine analog pro-drugs, used both in cancer and virosis therapies. GMPKs have been characterized as monomeric enzymes both in eukaryote and prokaryote organisms. The primary structure of GMPK from Haemophilus influenzae contains one Trp and 10 Tyr residues responsible for its fluorescence emission. The fluorescence spectrum of GMPK presents the Trp emission, at the wavelength of 320 nm. The modification of the protein fluorescence spectrum during the binding of GMP and ANS to it was studied. The protein-ligand binding process takes place with moderated binding constants for both GMP and ANS ligands (KGMP = 3.3 ×10^4 M-1, KANS = 4.5 ×10^4 M-1). The temperature dependence of the fluorescence emission of GMPK was also monitored. The preliminary studies of GMPK by differential scanning calorimetry (DSC) confirm the value of the denaturation temperature observed in the fluorimetric experiments. Thus, the denaturation of this protein, observed by DSC, is taking place on a narrow temperature interval, around the temperature value of 50 °C.