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Methyl ¹H double quantum CPMG

Module name​

"cpmg_ch3_1h_dq"

Description​

Measures methyl proton chemical exchange recorded on site-specifically 13CH3-labeled proteins in a highly deuterated background. Magnetization is initially anti-phase and is read out as anti-phase. The calculation uses a simplified scheme that includes only (6n)×(6n) basis set, two-spin matrix, where n is the number of states:

{ 2HDQxCz(a), 2HDQyCz(a), 2HzCz(a), HDQx(a), HDQy(a), Hz(a), 2HDQxCz(b), 2HDQyCz(b), 2HzCz(b), HDQx(b), HDQy(b), Hz(b), ... }

Reference​

  • Gopalan, T. Yuwen, L.E. Kay, and P. Vallurupalli. J. Biomol. NMR 72, 79-91 (2018)

Example​

An example, where joint fit of methyl ¹H double quantum CPMG (cpmg_ch3_1h_dq) and methyl ¹H triple quantum CPMG (cpmg_ch3_1h_tq) experiments is performed, is available here.

Sample configuration file​

experiment.toml
## This is a sample configuration file for the module 'cpmg_ch3_1h_dq'

[experiment]

## Name of the chemex module corresponding to the experiment
name = "cpmg_ch3_1h_dq"

## CPMG relaxation delay, in seconds
time_t2 = 0.04

## Position of the 1H carrier during the CPMG period, in ppm
carrier = 0.5

## 1H 90 degree pulse width of CPMG pulses, in seconds
pw90 = 12.0e-6

## Performs CPMG using 90-180-90 composite pulses [optional, default: true]
# comp180_flg = true

## Enters the CPMG period with equal amount of initial IP and
## AP DQ magnetizations [optional, default: false]
# ipap_flg = false

## 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]
  L3HD1-CD1  = "L3CD1-QD1.out"
  L3HD2-CD2  = "L3CD2-QD2.out"
  I12HD1-CD1 = "I12CD1-QD1.out"
  V25HG1-CG1 = "V25CG1-QG1.out"
  V25HG2-CG2 = "V25CG2-QG2.out"
  M36HE-CE   = "M36CE-QE.out"