Dear Vincent, first, certainly, you can continue to a higher resolutions distinguishing further details :
3.3 A - nucleic acid pairs .... 1.2 A - atomic details 0.9 A - deformation density (by the way, there was a relevant work, I think, by E.Blanc and G.Bricogne beginning of 2000, about some crucial high-resolution cut-offs). Second, a convenient scale for this detail analysis is logarithmic (we discussed this a few years ago in Acta Crsyt D); the limits you are talking about become more or less uniform in this scale. Third, at low resolution the situation is not at all so simple as you wrote. For example, images at 10-12 A may show neither "more ordered envelopes" nor "secondary structure elements" but only a "big mess". This is really the "worse resolution" to work with. I can send / give you off-list some illustrations. Best regards, Sacha Urzhumtsev ----- Le 28 Nov 17, à 15:44, vincent Chaptal <vincent.chap...@ibcp.fr> a écrit : > Hi, > I've been searching but can't find what I am looking for so I thought I ask > specialists. > I am curious about the link between resolution limits of reflections on the > detector, and what features are ordered in real space. > I saw the great movie by James Holton on resolution and features in the > electron > density map, but I am looking for something more general. > I am thinking that a reflection on the detector originates from something > ordered within the crystal. The level of order would be different at different > resolution. > If you can help me fill the void in this phrase: > I see spots at __A resolution, therefore I know that _____ features are > ordered > in my crystal. > intuitively, I would build the following scale: > 20A : the envelope is ordered > 10A: a finer envelope is ordered > 6A: alpha helices are ordered > 4-5A: beta sheets are ordered and some residues > 3-4A: residues start to be ordered > >3A: more and more order. > Has this been described somewhere? I would appreciate any comments and > reevaluation of this scale. > Thank you in advance. > All the best > Vincent > -- > Vincent Chaptal, PhD > Institut de Biologie et Chimie des Protéines > Drug Resistance and Membrane Proteins Laboratory > 7 passage du Vercors > 69007 LYON > FRANCE > +33 4 37 65 29 01 > http://www.ibcp.fr
