Long-range 15N-1H correlation experiments for histidine rings

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2D [15N, 1H] long-range HSQC for His rings

Varian

File:GNfhsqc His.tgz: long range 15N-1H HSQC package - tested with VnmrJ 2.1B

This pulse sequence correlates aromatic H-C protons of His with ring nitrogens. Modified from BioPack gNfhsqc.c by adding 90-180-90 composite 180 pulses on 15N and changing decoupling options.

Tarball contents:

  • vnmrsys/psglib/gNfhsqc_His.c
  • vnmrsys/templates/layout/gNfhsqc_His/
  • vnmrsys/maclib/gNfhsqc_His

Installation:

  • Save the gNfhsqc_His.tgz file into VnmrJ user home directory (e.g. /home/vnmr1).
  • Extract with tar xvzf gNfhsqc_His.tar - existing files will be overwritten!

Default settings

  • JNH=22.75 Hz, to refocus 1J_NH couplings
  • 15N carrier at 200 ppm
  • 15N spectral width is 200 ppm
  • 13C carrier at 125 ppm
  • 15N decoupling during acquisition is off
  • 13C 40 ppm WURST decoupling during acquisition
  • 3-9-19 for water suppression

Points to consider:

  • WURST decoupling produces strong side-bands, especially harmful if your protein has a His-tag. It is thus recommended to set 13C decoupling to GARP.
  • On some instruments 90-180-90 composite 15N pulses may be longer than the corresponding 3-9-19 delay, creating a negative delay in the pulse sequence (look for the '?' in 'dps'). In this case use traditional WATERGATE instead of 3-9-19

There is also the rna_WGgNhsqclr setup macro from BioPack. This macro loads the rna_WGgNhsqc.c pulsesequece with parameters for long-range correlations.

Reference: J. G. Pelton, D. A. Torchia, N. D. Meadow and S. Roseman, Protein Sci 1993 2: 543-558

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