Hi All, A problem with this is what do we mean by 1.2A data? I/sigma = 2 etc? (not intended to restart the old resolution cutoff discussion)
>From a personal point of view, I like to consider what features I can see in the experimental electron density - so relatively high resolution is when I can see the hole (in coot, default I/sig limits) in Phe / Tyr. When I can see both holes in Trp I tend to think of it as really quite high resolution, and when you can tell the difference between C and O in the map from the size of the blobs, well to me that is properly atomic ;o) This probably correlates with the 1.2A rule, anyway. Low resolution data would be, to me, when you can see the main chain but not see the side chains so well. However, this is from somebody who has spent a lot of time looking at structural genomics data, so if you are into membrane proteins etc. your perspective will most likely be different. In passing, it is interesting to take a historical perspective on this and look at some old papers - for example one on phase determination for Myoglobin at a resolution of 2A (Dickerson, Kendrew & Strandberg, 1961, Acta Cryst 14, 1188) where the problem of the number of reflections to consider required a change in approach for the phasing, using a "digital solution" - there were some 9000 or so reflections as opposed to 400 for the 6A structure... Looking at the same problem today, with SAD data to 1.2A, would take several seconds with shelx. Just my 1.5 p worth... Cheers, Graeme 2008/5/15 Bryan W. Lepore <[EMAIL PROTECTED]>: > > On Thu, 15 May 2008, William Scott wrote: > > > On May 15, 2008, at 10:01 AM, Ed Pozharski wrote: > > > > > 1.2A (not surprisingly since this is about the length of covalent > > > bond). > > > > > > > A carbon-carbon single bond is about 1.55 Å. > > > > the van der Waals radius of hydrogen is 1.2A (Eisenberg/Crothers, Pauling, > 1960 ). this distance is referred to in "Sheldrick's 1.2A rule". > > http://scripts.iucr.org/cgi-bin/paper?ad0198 > > -bryan
