Thursday, April 09, 2009

J. Am. Chem. Soc., Article ASAP

15N−15N Proton Assisted Recoupling in Magic Angle Spinning NMR
Jzef R. Lewandowski†, Gal De Pape‡, Matthew T. Eddy and Robert G. Griffin*

We describe a new magic angle spinning (MAS) NMR experiment for obtaining 15N−15N correlation spectra. The approach yields direct information about the secondary and tertiary structure of proteins, including identification of α-helical stretches and interstrand connectivity in antiparallel β-sheets, which are of major interest for structural studies of membrane proteins and amyloid fibrils. The method, 15N−15N proton assisted recoupling (PAR), relies on a second-order mechanism, third spin assisted recoupling (TSAR), used previously in the context of 15N−13C and 13C−13C polarization transfer schemes. In comparison to 15N−15N proton-driven spin diffusion experiments, the PAR technique accelerates polarization transfer between 15N’s by a factor of 102−103 and is furthermore applicable over the entire range of currently available MAS frequencies (10−70 kHz).

1 comment:

Sabu Varghese said...

PAR claims that the recoupling is a second order mechanism when compared to other SSNMR recoupling methods which employ first order recoupling mechanism. Can some one explain what makes the actual difference between PAR and and PDSD like experiments in terms of those mechanism?