The impact of pulse duration on composite WATERGATE pulse.
As an effective method for solvent suppression, WATERGATE is widely used in high resolution NMR spectroscopy. It is usually composed of a number of pulses separated by constant intervals. However, theoretical and experimental analyses indicate that narrower bandwidth and lower intensities around the secondary suppression points occur in the excitation profile of the composite WATERGATE. The excitation profile distortion is caused by the chemical shift evolution during the RF pulses. The higher the ratio of pulse duration to the inter-pulse delay is, the severer the profile distorts. Therefore, in high magnetic fields, the effect will be serious when WATERGATE is applied to some biological samples whose resonances distribute over a wide range. As can be seen obviously by applying WATERGATE to detect a RNA-protein mixture sample in an 800 MHz spectrometer, the resonances of the imino protons were partially suppressed by showing decreased intensities, though the intended secondary suppression points were set far away from them. In this article, we proposed an optimized WATERGATE that could effectively compensate the chemical shift evolution during the RF pulses, and relieve the excitation profile distortion. The optimized experiment will be a good way to retain the imino signal intensities when WATERGATE is applied to detect the RNA samples in high magnetic field.
Wang
Jingjing
J
State Kay Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
Zhang
Xu
X
Sun
Peng
P
Jiang
Xianwang
X
Jiang
Bin
B
Cao
Chunyang
C
Liu
Maili
M
D000465:Algorithms; D045424:Complex Mixtures / Q000032:analysis* / Q000737:chemistry; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D011506:Proteins / Q000032:analysis* / Q000737:chemistry; D012313:RNA / Q000032:analysis* / Q000737:chemistry; D012815:Signal Processing, Computer-Assisted
D045424:Complex Mixtures; D011506:Proteins; D012313:RNA