High Field DNP and EPR in Biological Systems

Massachusetts Institute Of Technology, Cambridge MA

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Abstract

DESCRIPTION (provided by applicant): The proposed research is focused on high frequency dynamic nuclear polarization (DNP)/NMR, electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR). We plan CW and pulsed DNP experiments and primarily time domain EPR and ENDOR spectroscopy. The research will develop new magnetic resonance technology and methodology, and address structural questions in a number of interesting biochemical systems. DNP: The DNP experiments can be divided into four (4) areas of endeavor. (1) CW MAS-DNP focuses on the design and construction of equipment to complete a 460 GHz/700 MHz DNP/NMR spectrometer and on applications of DNP to structural biology of membrane and amyloid proteins, the soluble protein GB1 and 17O MQMAS experiments. (2) T-Jump DNP experiments for enhancing NMR signals in spectra of liquids will be developed further. (3) Biradical polarizing agents will be synthesized to improve the efficiency of DNP. (4) Pulsed DNP experiments are planned that will enhance the efficiency of electron-nuclear polarization transfer. EPR/ENDOR: We plan to address questions in five (5) areas with EPR and ENDOR. (1) We propose to develop a simple method for spin counting in proteins containing free radicals (2) We plan to develop a freeze quench apparatus and examine the kinetics of formation of short time radical intermediates in RnR chemistry. (3) We will reexamine high field EPR and ENDOR spectra of apogalactose oxidase as a path to understand the identical spectra observed in the "3 minute" intermediate of E441Q RnR and gemcitabine. (4) We plan to determine the alignment of peptides in amyloid fibrils with TOAC labeling. (5) With the development of a 140 GHz gyroamplifier we intend to implement a number of advanced EPR techniques at high field.