HIGH FIELD DNP AND EPR IN BIOLOGICAL SYSTEMS

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

This proposal outlines investigation of proteins and model systems with three innovative magnetic resonance techniques: high frequency dynamic nuclear polarization (DNP), time domain 140 GHz electron paramagnetic resonance (EPR), and electron nuclear double resonance (ENDOR). The research plan is divided into four Specific Aims: (1) Development of CW and Pulsed DNP methods involving high Ble fields, the CROSS-effect, and electron-nuclear cross polarization. (2) Applications of DNP to biological problems include studies of alpha-spectrin SH3 crystals, oriented bacteriorhodopsin and Pfl bacteriophage, amyloid fibrils, and O-17 MQMAS. Each of these projects involves an area of magnetic resonance where the enhanced signal intensities available with DNP could have a significant impact. (3) Investigations of pulsed EPR and ENDOR investigations for four different systems: (a) the "3- minute" radical observed in the E441Q mutant of ribonucleotide reductase (RNR); (b) a model for the X-intermediate formed on combining Fe and apoRNR, and the X-intermediate in the protein itself; (c) the tyrosyl radical in RNR from yeast; (d) study of a difluorinated inhibitor of RNR, gemcitabine, with both Class I and Class II RNR's. (4) Development of advanced pulsed EPR/ENDOR at 140 GHz. These include TRIPLE, TRAPS, DEER and MQENDOR with the goal of enhancing the versatility and resolution of methods available to examine protein free radicals.