Interactions of Biphenyl Therapeutic Drugs and Their Binding Sites in Voltage-Gated Na+ Channels by Nmr Spectroscopy and Mass Spectrometry

Voltage-gated Na+ channels are the primary targets of many important therapeutic drugs, including local anesthetics and anticonvulsants. The main purpose of this project is to provide novel insights into the structural relationship between the therapeutic drugs and their drug target in Na+ channels. In this proposal, we will focus on the detail orientation of biphenyl groups and amine group in desirable structures of several clinically useful drugs, and study the effect of structural and conformational properties related to inhibition of inactivated Na+ channel by using NMR spectroscopy and mass spectrometry (MS). Further molecular modeling will be performed to identify possible inhibitor-receptor interactions that may be critical for recognition and signal transduction of inactivated Na+ channel. We have demonstrated the interaction of phenytoin and its binding site in DI-S6 segment of Nav1.2 by NMR and molecular modeling studies recently. With the well established methodologies in our lab, the design of this study is as follows. First year: (a) Apply NMR and MS methodologies and incorporate with molecular modeling for analysis of the therapeutic drugs and DVI-S6 complex. (b) Design amide hydrogen exchange MS (HXMS) to investigate the dynamical and structural properties of the non-covalent complex between phenytoin and LIII-IV. Second year: (a) Continue to exam and analyze the drugs binding site in DIII-S6 by drugs titrations and compare the complex of S6 segments within DI, DIII, and DIV domains for further recognizing drugs-binding residues. (b) Refine and evaluate the feasibility of HXMS in our experimental development. Third year: (a) Continue the interactions studies between biphenyl therapeutic drugs and four S6 segments. (b) Extend the drug interaction studies with the outer P-loop of the Na+ channels. Such an approach, in principle, provides the information to determine the three dimensional biologically active conformation for the drug molecules. The results obtained from this study may provide alternative medications that produce safe, effective and non-addicting analgesic pharmaceuticals.

Project ID:PA9706-0691
External Project ID:NSC96-2113-M182-003-MY2