Changes

The Davis et al., 1994 2-site off-resonance fast exchange relaxation dispersion model for [[R1rho-type data]]. It extends the [[M61]] model to off-resonance data, hence it collapses to this model for on-resonance data. The model is labelled as '''DPL94''' in [[Relaxation dispersion citation for relax|relax]].

The DPL94 model has the parameters {$R_{1\rho{:R1rhoprime}}'$, $...$, $\Phi_{ex{:Phiex}}$, $k_{ex{:kex}}$}.

=== Essentials === {{note|{{:R1}} should be provided in rad/s, the SI default unit for this relaxation rate.}} It is essential to read in $R_{1\rho{:R1}}'$ values before starting a calculation:<br>

 {{collapsible script| type = relax script| title = At time of writing (March 2014) the parameters in relax was were stored as:demonstrated in this script.<source | lang ="python">| script =

<[http:/source>/www.nmr-relax.com/manual/Dispersion_model_summary.html Please see the summary of the model parameters here.]

# $R_{1\rho{:R1rhoprime}}'$ = <code>spin.r2</code> (Fitted)# $\Phi_{ex{:R1rho}} = <code>spin.r2eff</code> (Back calculated)# {{:Phiex}}$ = <code>spin.phi_ex</code> (Fitted)# $k_{ex{:kex}}$ = <code>spin.kex</code> (Fitted)#{{:R1}} = <code>spin.ri_data['R1']</code> (Loaded) Please also see this thread: http://thread.gmane.org/gmane.science.nmr.relax.devel/5164 == Equation - re-written forms ==Discussed in: http://thread.gmane.org/gmane.science.nmr.relax.devel/5207 * {{#lst:Citations|Evenäs01}}* {{#lst:Citations|KempfLoria04}}* {{#lst:Citations|Massi05}}* {{#lst:Citations|Palmer01}}* {{#lst:Citations|PalmerMassi06}}* {{#lst:Citations|TrottPalmer02}} Different graphs. == The {{:R1rho}}: {{:R2}} or {{:R2eff}} as function of effective field in rotating frame: {{:omegaeff}} == === Discussion ===It is clear that there is no real name for the pseudo-parameter. It looks like that {{:Reff}} was Art's original way of denoting this and that he has now changed to {{:R2}} instead. <br>But if one look at the reference for the [[TP02|TP02 dispersion model]], one will see yet another notation: Here {{:R2}} does not contain the {{:Rex}} contribution. Also, {{:Reff}} is absent of {{:Rex}}. <br>But in Art's Protein Science paper (Ref [5]), the definition {{:R2}} = {{:R2zero}} + {{:Rex}} is used. The [[MP05|MP05 model reference]] also does not use {{:Reff}}. The {{:Reff}} parameter name is confusing and it seems to have been dropped from 2005 onwards. The {{:Reff}} name appears to be specific to Art Palmer's group and as he himself has dropped it, then it would be best to avoid it too.  Ref [2], Equation 27. Here the calculated value is noted as: R_eff: <math>R_{\text{eff}} = R^{0}_2 + R_{ex} = R_{1\rho}' + R_{ex} = R_{1\rho} / \sin^2(\theta) - R_1 / \tan^2(\theta)</math> <br>Ref [3], Equation 20. Figure 11+16, would be the reference. Here the calculated value is noted as: R_2: <math>R_{2} = R_{1\rho} / \sin^2(\theta) - R_1 / \tan^2(\theta)</math>. <br>Ref [4], Equation 43. <math>R_{\text{eff}} = R_{1\rho} / \sin^2(\theta) - R_1 / \tan^2(\theta)</math> <br>Ref [5], Material and Methods, page 740. Figure 4 would be the wished graphs. Here the calculated value is noted as: R_2: <math>R_{2} = R^{0}_2 + R_{ex}</math> The following suggestions for the definition of the pseudo-parameters, which can be extracted, is then: <math>R_2 = R^{0}_2 + R_{ex} = R_{1\rho}' + R_{ex} = R_{1\rho} / \sin^2(\theta) - R_1 / \tan^2(\theta) = \frac{R_{1\rho} - R_1\cos^2(\theta)}{\sin^2(\theta)}</math>

* Davis, D., Perlman, M., and London, R. (1994). Direct measurements of the dissociation-rate constant for inhibitor-enzyme complexes via the T1rho and T2 (CPMG) methods. ''J. Magn. Reson.'', '''104'''(3), 266–275. ([http{{#lst://dx.doi.org/10.1006/jmrb.1994.1084 10.1006/jmrb.1994.1084])Citations|Davis94}}

The [[Relaxation dispersion citation for relax|implementation of the DPL94 model in relax ]] can be seen in the:* [http://www.nmr-relax.com/manual/DPL94_2_site_fast_exchange_R1_modelThe_DPL94_2_site_fast_exchange_R1_rho_model.html relax manual],

[[Category:Relaxation_dispersionModels]][[Category:Dispersion models]][[Category:Relaxation dispersion analysis]]