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Since I was being cited (*blush*), I should add that I very much doubt that 160 is very close to the upper limit, given the relative ease with which (any!) dual space methods seem to deal with that dataset, if run properly (RTFM!!!). "Careful data collection" mostly involved paying radiation damage its due respect: sacrificing resolution to low exposure times, using fresh crystal volumes, that sort of healthy paranoia. Not that there was no damage (which only goes to show) but it could have been a lot worse. I did also have a fairly favourable Se/protein ratio (8 Se / 260 aa) and there was high NCS (two decamers) which obviously helped phase improvement. I heard at least one Person Who Probably Knows (ZO) suggest that the NCS itself would help dual-space methods (something about intensity distributions, I did not catch the full argument); although at least one other Person Unlikely Not To Know (George Sheldrick) dismissed that it would make a difference (if memory serves me). phx > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Eleanor Dodson > Sent: 21 October 2005 09:00 > To: Ho-Leung Ng > Cc: [email protected] > Subject: Re: [ccp4bb]: finding heavy atom sites in large structures > > Ho-Leung Ng wrote: > > >*** For details on how to be removed from this list visit the *** > >*** CCP4 home page http://www.ccp4.ac.uk *** > > > > > >Hello, > > > > I am working on a large protein complex and would like to know > >what are the protein size limits for finding heavy atom sites (not > >clusters), either by Patterson-based or dual space recycling methods. > >For example, what is the largest ASU that has been solved by > >selenomethionine phasing? > > > > > >Thanks, > >ho > >UC Berkeley > > > > > > > > > > > The most I know of is the 160 Se in a pentamer solved by > Frank von Delft . His email is: not sure if/where it is > published Frank von Delft <[EMAIL PROTECTED]> > > He could find them using dual space methods, but he had > collected the data exquisitely carefully.. You prob. need to > do that too. > You are looking for very small diffs > Eleanor > >
