Dear Vito I looked at the examples of I3C in 3e3d, 3e3s and 3e3t and certainly the latter two show clear 2Fo-Fc for several I3Cs at a range of occupancies. So my mention of the different difference maps’ effectiveness does not apply. Hermann and Eleanor suggestions hopefully will explain your I3C map visibility you showed.... Best wishes John
Emeritus Professor of Chemistry John R Helliwell DSc_Physics > On 10 Jun 2020, at 09:39, John R Helliwell <jrhelliw...@gmail.com> wrote: > > Dear Vito, > The I3C isn't like the platins as a challenge to the 2Fo-Fc map. > It maybe is more akin to the situation we described here:- > https://onlinelibrary.wiley.com/doi/abs/10.1107/S0907444903004219 > ie what does your Fo-Fc map, with three iodines placed, at the correct > occupancy, look like? > Best wishes, > John > > Emeritus Professor John R Helliwell DSc > > > >>> On 10 Jun 2020, at 09:34, Vito Calderone <calder...@cerm.unifi.it> wrote: >>> >> Dear Pierre, >> I was in particular talking of 2FoFc refinement maps. >> In the attached picture for example you can see the 2FoFc map contoured at 1 >> sigma level of an I3C molecule bound to a protein where for I3C the only >> visible density is that of iodines whereas the density of the other atoms of >> the ligand is insignificant. >> Best regards >> >> Vito >> >> -----Messaggio originale----- >> Da: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> Per conto di LEGRAND Pierre >> Inviato: mercoledì 10 giugno 2020 09:31 >> A: CCP4BB@JISCMAIL.AC.UK >> Oggetto: Re: [ccp4bb] Heavy atom vs light atoms density >> >> Dear Vito, >> Could you precise in what kind of maps are you experiencing these effects: >> 2FoFc refinement maps or experimental phasing ? >> I had this kind of effects long ago in experiemental phasing due to Fourier >> transform ripple effects. This could be due to scaling problems, low >> resolution truncation or incompletness (maybe intensity overloads). >> Another source condition could be local X-ray dose degradation due to the >> high absoption of the metals. >> Best regards, >> Pierre Legrand >> PROXIMA-1, SOLEIL >> ________________________________________ >> De : CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] de la part de Vito >> Calderone [calder...@cerm.unifi.it] Envoyé : mercredi 10 juin 2020 08:42 À : >> CCP4BB@JISCMAIL.AC.UK Objet : [ccp4bb] Heavy atom vs light atoms density >> >> Dear All, >> many of us have probably experienced that, in the diffraction >> of protein ligands containing heavy atoms (cisPt, I3C, etc), the >> overwhelming electron density of the metal can totally flatten that of the >> light atoms around (or rather make it look insignificant). >> Is anyone aware of an article/review (to use as a reference) in which this >> is clearly stated/pointed out? >> Best regards >> >> Vito Calderone >> >> >> >> ________________________________ >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >> >> ######################################################################## >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >> >> This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing >> list hosted by www.jiscmail.ac.uk, terms & conditions are available at >> https://www.jiscmail.ac.uk/policyandsecurity/ >> >> ######################################################################## >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >> >> This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing >> list hosted by www.jiscmail.ac.uk, terms & conditions are available at >> https://www.jiscmail.ac.uk/policyandsecurity/ >> <I3C_3.png> ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
