Dear Oliviero, For sure cysteines can be disordered. Sometimes you can find one conformation reduced and another conformation oxidised if the cysteine is solvent exposed. Also in well-resolved structures you can see a cysteine taking part in a disulphide bond, but only partially, one conformation being unbound. This can have to do with how you treated your protein with reducing agents but probably also depend on how easily reduced the disulphide bond is. Also cysteines can be modified by beta-mercaptoethanol if this chemical is added in large amounts and the cysteines are solvent exposed. More seldom I have seen double conformation alone of cysteines but I guess this may occur as well.
It can be difficult to correctly model oxidised and reduced or native cysteines in the same residue since the residue names differ (and you can only have one name). Depending on occupancy I usually use CYS only if lower occupancy of the oxidised form or if higher occupancy of the oxidised form CSO for both (could be other species too), possibly with zero occupancy on the oxygen missing. Maybe there is better suggestions? Sorry not to be able to share any references. Good luck! Best regards, Maria > On 22 Apr 2024, at 10:55, Italo Carugo Oliviero > <olivieroitalo.car...@unipv.it> wrote: > > Dears, > is it possible for a cysteine to be conformationally disordered? It seems > strange to me. If it were, it would almost certainly be exposed to the > solvent and thus easily oxidized irreversibly. Do you perhaps have any > information on conformationally disordered cysteines? > I thank you, > Oliviero > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > Maria Håkansson, PhD, Principal Scientist SARomics Biostructures AB Medicon Village SE-223 81 Lund, Sweden Mobile: +46 (0)76 8585706 Web: www.saromics.com ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?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/
