Hi! another possibility is to change the ionic force slightly (like the salt content), so that the interactions between the two proteins is not that strong (and they don't precipitate). Good luck! Nurit.
> Date: Thu, 13 Dec 2007 05:51:59 +0000> From: [EMAIL PROTECTED]> Subject: Re: > [ccp4bb] protein precipitated when they formed a complex> To: > [email protected]> > Hi Jerry,> > have you tried tinkering with the pH?> > I have had similar situation, where two normally soluble proteins> > precipitated upon mixing at pH 7.5, my "stock" buffer. Altering the pH> > showed that the complex that was only soluble at pHs lower than 6.> > Looking > at your pIs, it strikes me that in between 6.5 and 10 is 8,> which is where > most peoples "stock buffers" live - if your complex has> a pI at your current > pH, then it's not going to be at its most> soluble.> > Failing that, the NDSB > solubising agents are worth a shot...> > Hope this helps,> > David.> > On > 12/12/2007, Jerry McCully <[EMAIL PROTECTED]> wrote:> >> > Dear All,> >> > > Recently I posted a question about protein induced protein> > precipitation.> > > Firstly I'd like to thank many folks for their good ideas.> >> > Later on I > did a titration experiment with one protein concentration> > fixed at > 0.4mg/ml(about 10uM). Now it is clear that these two proteins> > > stoichiometrically precipitated when they formed a 1:1 complex. The excess> > > of individual proteins was just soluble in the buffer.> >> > How come these > two proteins co-precipitated when they formed a complex?> >> > Does anyone > know some methods to keep the complex soluble enough for> > crystallization?> > >> > By the way, there is some additional information about the individual> > > components. One has a pI of 6.5, and the other has a pI of 10.> >> >> > Any > suggestions will be highly appreciated.> >> > Jerry McCully> >> >> >> >> > > ________________________________> > Get the power of Windows + Web with the > new Windows Live. Get it now!> > > -- > ============================> David > C. Briggs PhD> Father & Crystallographer> > http://personalpages.manchester.ac.uk/staff/David.C.Briggs/> AIM ID: > dbassophile> ============================ _________________________________________________________________ i’m is proud to present Cause Effect, a series about real people making a difference. http://im.live.com/Messenger/IM/MTV/?source=text_Cause_Effect
