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Pure in-phase ¹³C CPMG

Module name​

"cpmg_13c_ip"

Description​

Analyzes ¹³C chemical exchange in the presence of high power ¹H CW decoupling during the CPMG block. This keeps the spin system purely in-phase throughout, and is calculated using the (3n)×(3n), single-spin matrix, where n is the number of states:

{ Ix(a), Iy(a), Iz(a), Ix(b), Iy(b), Iz(b), ... }

The CW decoupling on ¹H is assumed to be strong enough (> 15 kHz) such that perfect ¹H decoupling can be achieved. In the case of CHD2 experiment, CW decoupling on 2H should be applied properly.

References​

  • D.F. Hansen, P. Vallurupalli, Lundström, Neudecker, and L.E. Kay. J. Am. Chem. Soc. 130, 2667-2675 (2008)
  • E. Rennella, Schuetz, and L.E. Kay. J. Biomol. NMR 65, 59-64 (2016)

Example​

An example use of the module, based on datasets measured for CHD2-labeled side-chain methyl groups, is given here.

Sample configuration file​

experiment.toml
## This is a sample configuration file for the module 'cpmg_13c_ip'

[experiment]

## Name of the chemex module corresponding to the experiment
name = "cpmg_13c_ip"

## CPMG relaxation delay, in seconds
time_t2 = 0.04

## Position of the ¹³C carrier during the CPMG period, in ppm
carrier = 18.0

## ¹³C 90 degree pulse width of CPMG pulses, in seconds
pw90 = 15.0e-6

## Equilibration delay at the end of the CPMG period, in seconds
## [optional, default: 0.0]
# time_equil = 0.0

## State of the observed resonance [optional, default: "a"]
# observed_state = "a"

[conditions]

## 1H Larmor frequency, in MHz
h_larmor_frq = 800.0

## Sample temperature, in Celsius [optional, depending on the kinetic model]
# temperature = 25.0

## Protein concentration, in M [optional, depending on the kinetic model]
# p_total = 500.0e-6

## Ligand concentration, in M [optional, depending on the kinetic model]
# l_total = 50.0e-6

[data]

## Directory containing the profiles [optional, default: "./"]
# path = "./"

## Option defining how intensity uncertainties are estimated.
## "file": uncertainties are taken from the profile files
## "duplicates": uncertainties are calculated from the duplicate points
## [optional, default: "file"]
# error = "file"

  ## List of the profile names and their associated filenames.
  ## The name of the spin systems should follow the Sparky-NMR
  ## conventions.
  [data.profiles]
  L3CD1  = "L3CD1-QD1.out"
  L3CD2  = "L3CD2-QD2.out"
  I12CD1 = "I12CD1-QD1.out"
  V25CG1 = "V25CG1-QG1.out"
  V25CG2 = "V25CG2-QG2.out"
  M36CE  = "M36CE-QE.out"