Hi Savvas, You're right. It shouldn't be O-glycosylation, since the protein is from Archaea and expressed in E. coli. Most possiblly, I think it's something wrong with the sequence.
Thanks for your help, Best, Vinson ________________________________ 发件人： Savvas Savvides <[email protected]> 收件人： Vinson LIANG <[email protected]> 抄 送： [email protected] 发送日期： 2010/11/24 (周三) 9:48:28 下午 主 题： Re: [ccp4bb] Strange density on Serine oxygen. Hi Vinson is O-glycosylation possible at all given the origin of the protein and the expression system used? best Savvas On 24 Nov 2010, at 14:42, Vinson LIANG wrote: Dear Savas and all, > > >Thank you very much for all your quick suggestions. > >I have tried Tyr and it turns out to fit the density very well. I will have >the >protein sequenced again to see if it is wrong sequece or O-linked >glycosylation. > >I'll let you know if it turns out to be O-linked glycosylation. > >All the best, > >Vinson > > ________________________________ 发件人： Savvas Savvides <[email protected]> >收件人： Vinson LIANG <[email protected]> >抄 送： [email protected] >发送日期： 2010/11/24 (周三) 9:27:31 下午 >主 题： Re: [ccp4bb] Strange density on Serine oxygen. > >Hi Vinson >Beyond the possibility for another type of residue as already suggested by >Phil >and Mark, there is also the possibility of O-linked glycosylation of the >serine >and threonine, if your protein undergoes such post-translational modification >and it has been expressed via an expression system that processes the protein >in >that way. >Ser/Thr tandems are well known targets for O-glycosylation >(http://www.cbs.dtu.dk/databases/OGLYCBASE/). > > >best regards >Savvas > > >---- >Savvas Savvides >Unit for Structural Biology @ L-ProBE >Ghent University >K.L. Ledeganckstraat 35, 9000 Ghent, Belgium >Ph. +32 (0)472 928 519 http://www.LProBE.ugent.be/xray.html > > > > >On 24 Nov 2010, at 13:10, Vinson LIANG wrote: > >Dear all, >> >>I'm refining a structure and find some strange triangle density on the oxygen >>of >>Ser and Thr at the C terminus. One picture of the strange density is attached >>here. Could anyone please give me some suggestions on what this could be? >> >>The buffer used during purification is PBS, Tris and NaCl. And >>crystallization >>condition contains PEG3,350 and Mg(NO3)2. >> >>Thank you all in advance for any suggestion. >> >>Best, >> >>Vinson Liang >> >> >> <triangle_density.gif> > > >
