EasySpin forum

Dear Professor Stoll,

Recently, following the last Easyspin update, I faced a problem regarding the reproducibility of my Q-band 2H Mims ENDOR spectra simulations. Using previous easyspin versions (i.e. 4.5.5 & -5.0.1), I could get the red spectrum in the attached top picture. It is identical to that previously published in the group (see Fig. 4 in Grimaldi et al, JBC 287, 2012). Using the same program with more recent easyspin versions (i.e. 5.1.11 & -5.2.11), the simulated spectrum shows an additional shoulder around 7.3 MHz (indicated with an asterisk in the attached bottom figure) and therefore appears more asymmetric in the central region. In my program (see attached file), all Euler angles are set to zero.

I hope you can kindly help me to understand the origin of this additional signal.

Thanks a lot in advance.

Best regards,

Maryam Seif Eddine

We will look into this. Can you please post the script you show in the figure? Post it as text.

Thank you for answering

This is the script I used to re-simulate the Mims-ENDOR spectrum (result published by Grimaldi, S., R. Arias-Cartin, et al. (2012), in J Biol Chem 287(7): 4662-4670) :

clear, clf, clc

Exp.Sequence = 'MimsENDOR';
Exp.Field = 1199.85;
Exp.tau = 0.200;
Exp.nPoints=512;
Exp.Range=[5.8 9.8];
Sys.Nucs = '2H';

% Parameters for orientation selection
Sys.S = 1/2;
Sys.g = [2.0061 2.0051 2.0023];
Exp.mwFreq = 33.68493;
Exp.ExciteWidth = 41.6;

Aiso=0.06/6.5;
T=+5.7/6.5;

Sys.A=[Aiso-T Aiso-T Aiso+(2*T)];
Sys.AFrame = [0 0 0]*pi/180;

Sys.Q = [0.044*4 0.2];
Sys.QFrame = [0 0 0]*pi/180; ,

Sys.lwEndor = 0.047;


load ('anrwt19tub3mej.mat');
x=anrwt19tub3mej(:,2);
y=anrwt19tub3mej(:,3);
y=y/sum(y);
plot(x,y);
[xsim,ysim]=saffron(Sys,Exp);
ysim = abs(ysim);
ysim=ysim/sum(ysim);

hold all;
plot (xsim,ysim);

This is a bug that got introduced in 5.0.21. It is now fixed in version 5.2.12 that just posted. Thanks for reporting!