Module mmq_cr72

The CR72 model extended for MMQ CPMG data, called the MMQ CR72 model.

Description

This module is for the function, gradient and Hessian of the MMQ CR72 model.

References

The Carver and Richards (1972) 2-site model for all times scales was extended for multiple-MQ (MMQ) CPMG data by:

• Korzhnev, D. M., Kloiber, K., Kanelis, V., Tugarinov, V., and Kay, L. E. (2004). Probing slow dynamics in high molecular weight proteins by methyl-TROSY NMR spectroscopy: Application to a 723-residue enzyme. J. Am. Chem. Soc., 126, 3964-3973. (DOI: 10.1021/ja039587i).

Links

More information on the MMQ CR72 model can be found in the:

• relax wiki,
• relax manual,
• relaxation dispersion page of the relax website.

Functions

r2eff_mmq_cr72(r20=None, pA=None, dw=None, dwH=None, kex=None, cpmg_frqs=None, inv_tcpmg=None, tcp=None, back_calc=None)
The CR72 model extended to MMQ CPMG data.

Variables

eta_scale = 0.353553390593

__package__ = 'lib.dispersion'

Imports: arccosh, cos, cosh, isfinite, fabs, log, min, max, sin, sqrt, sum, fix_invalid, masked_greater_equal, masked_where

Function Details

r2eff_mmq_cr72(r20=None, pA=None, dw=None, dwH=None, kex=None, cpmg_frqs=None, inv_tcpmg=None, tcp=None, back_calc=None)

The CR72 model extended to MMQ CPMG data.

This function calculates and stores the R2eff values.

Parameters:

• r20 (numpy float array of rank [NS][NM][NO][ND]) - The R2 value in the absence of exchange.
• pA (float) - The population of state A.
• dw (numpy float array of rank [NS][NM][NO][ND]) - The chemical exchange difference between states A and B in rad/s.
• dwH (numpy float array of rank [NS][NM][NO][ND]) - The proton chemical exchange difference between states A and B in rad/s.
• kex (float) - The kex parameter value (the exchange rate in rad/s).
• cpmg_frqs (numpy float array of rank [NS][NM][NO][ND]) - The CPMG nu1 frequencies.
• inv_tcpmg (numpy float array of rank [NS][NM][NO][ND]) - The inverse of the total duration of the CPMG element (in inverse seconds).
• tcp (numpy float array of rank [NS][NM][NO][ND]) - The tau_CPMG times (1 / 4.nu1).
• back_calc (numpy float array of rank [NS][NM][NO][ND]) - The array for holding the back calculated R2eff values. Each element corresponds to one of the CPMG nu1 frequencies.