ИСТИНА

Nuclear Magnetic Resonance (NMR) spectroscopy gives a unique opportunity to study dynamical properties of biological macromolecules. This information is of particular interest for understanding the nature of ligand-protein interactions and mechanism of enzyme behavior. We have measured 15N NMR relaxation parameters to explore dynamical properties of human ternary dihydrofolate reductase (DHFR) complex with cofactor NADPH and antibacterial drug trimethoprim. DHFR catalyses the NADPH-dependent reduction of folate and dihydrofolate to tetrahydrofolate. Since the latter is an important cofactor in the biosynthesis of purines and amino acids, DHFR has proved to be an excellent target for antifolate drugs that act by inhibiting the enzyme in parasitic or malignant cells. The antibacterial effectiveness of antibacterial drug trimethoprim (TMP) is due to its significantly increased binding to the bacterial enzyme compared with the binding to the vertebrate form. In order to explore the origins of the specific interaction of TMP to the bacterial DHFR, information on structure and dynamics of human DHFR complex with TMP and NADPH was obtained and compared with similar data for analogues bacterial complex. The most prominent differences between bacterial and vertebrate forms were observed at comparison of dynamic properties of these two complexes.