Hi Liliana, May be it would be good to know if this adduct was formed during crystallization or protein was modified prior to crystallization. One could consider performing a protease digestion, followed by LC-MS/MS to determine the molecular weight of the adduct and then work backwards to account for the difference in dalton.
Good Luck, Partha On Mon, Dec 18, 2023 at 9:14 AM Liliana Margent < lmarg...@gradcenter.cuny.edu> wrote: > Hi there, We’ve been having an issue in trying to clear regions of Fo-Fc > density from a few cysteines during the refinement process. We were > wondering if anyone had seen something similar so they could offer some > insight on the likely chemistry at hand, and a potential refinement > solution. Attached are two images of the observed extra density at two > cysteines, 505 and 518. We have modeled acetylated cysteine, > s-hydroxycysteine, and s-mercaptocysteine but it does not solve the > density. The protein in question is a Protein Tyrosine Phosphatase known as > STEP (PTPN5), with data collected to a resolution of 1.79 Å. The crystals > were grown in bis-tris pH 6.65, 200mM Li2SO4, ~30% PEG3350. Of note, prior > to data collection the crystal was conserved at room temp for long time > where it dried, and was subsequently rehydrated with mother liquor. Thank > you so much. > ------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > ######################################################################## 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/
