title: (15)N-(15)N proton assisted recoupling in magic angle spinning NMR.
abstract: We describe a new magic angle spinning (MAS) NMR experiment for obtaining (15)N-(15)N correlation spectra. The approach yields direct information about the secondary and tertiary structure of proteins, including identification of alpha-helical stretches and interstrand connectivity in antiparallel beta-sheets, which are of major interest for structural studies of membrane proteins and amyloid fibrils. The method, (15)N-(15)N proton assisted recoupling (PAR), relies on a second-order mechanism, third spin assisted recoupling (TSAR), used previously in the context of (15)N-(13)C and (13)C-(13)C polarization transfer schemes. In comparison to (15)N-(15)N proton-driven spin diffusion experiments, the PAR technique accelerates polarization transfer between (15)N's by a factor of approximately 10(2)-10(3) and is furthermore applicable over the entire range of currently available MAS frequencies (10-70 kHz).
authors.affiliation: Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Józef R
authors.initials: JR
authors.lastname: Lewandowski
authors.forename: Gaël
authors.initials: G
authors.lastname: De Paëpe
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Eddy
authors.forename: Robert G
authors.initials: RG
authors.lastname: Griffin