Heating caused by radiofrequency irradiation and sample rotation in C-13 magic angle spinning NMR studies of lipid membranes

• Application of rapid sample rotation and radiofrequency irradiation in magic angle spinning (MAS) NMR of lipid bilayers can significantly increase the sample temperature. In this work, we studied the extent of heating during the acquisition of H-1-decoupled C-13 MAS spectra of hydrated dimyristoylphosphatidyl-choline (DMPC) in the L. phase. First, we describe a simple procedure for determining the increase in temperature by observing the shift of the H-1 water signal. The method is then used to identify and assess the various factors that contribute to the sample heating. The important factors discussed in this paper include: (i) the spinning speed, (ii) the variable-temperature gas pressure, (iii) the rotor geometry, (iv) the power, duration and frequency of the radiofrequency irradiation and (v) the hydration level. A comparison of different heteronuclear decoupling schemes in terms of their ability to produce highly resolved C-13 spectra of DMPC is also reported.

Keyword

NMR

C-13 NMR

H-1 NMR

magic angle spinning

cross-polarization magic angle spinning

magic angle spinning heating

radiofrequency heating

heteronuclear decoupling

lipid membrane samples

nuclear-magnetic-resonance

band decoupling sequence

solid-state nmr

liquid-crystals

temperature-gradients

cross-polarization

mas nmr

chemical-shift

biological-membranes

dipolar

Publication and Content Type

ref (subject category)

art (subject category)