AMORE-HX: a multidimensional optimization of radial enhanced NMR-sampled hydrogen exchange
The Cartesian sampled three-dimensional HNCO experiment is inherently limited in time resolution and sensitivity for the real time measurement of protein hydrogen exchange. This is largely overcome by use of the radial HNCO experiment that employs the use of optimized sampling angles. The significant practical limitation presented by use of three-dimensional data is the large data storage and processing requirements necessary and is largely overcome by taking advantage of the inherent capabilities of the 2D-FT to process selective frequency space without artifact or limitation. Decomposition of angle spectra into positive and negative ridge components provides increased resolution and allows statistical averaging of intensity and therefore increased precision. Strategies for averaging ridge cross sections within and between angle spectra are developed to allow further statistical approaches for increasing the precision of measured hydrogen occupancy. Intensity artifacts potentially introduced by over-pulsing are effectively eliminated by use of the BEST approach.
KeywordsHydrogen exchange Radial sampling Angle selection Two-dimensional FT
Supported by the Mathers Foundation, NIH grant DK 39806 and an NSF MRSEC award (DMR-0520020). J.M.G. is supported by NIH predoctoral training grant GM 008275. We thank Alison Wand and Dr. Sabrina Bédard for construction of the MBP expression vector and Shoshanna Pokras for helpful discussion.
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