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Re: [ccp4bb] counting constraints? |
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CCP4bb navigationCCP4bb <-- 2008 <-- February 2008 <-- 14 February 2008Subject: Re: counting constraints? From: Ian Tickle I {- dot -} Tickle {- at -} ASTEX-THERAPEUTICS {- dot -} COM Date: 2008-02-14 Sorry I re-read your e-mail & realised you're asking a slightly different question from the one I answered. Of course you count the restraints in your structure, not the ones in the dictionary, so in the example you give there would be 4 not 1. Each bond, angle, torsion, VDW contact, B-factor difference, NCS restraint etc in the structure counts as one. For planes you formally should count (#atoms_in_plane - 3) since 3 of the planar deviations are not independent (i.e. 3 points define a plane). And of course as Bart said they are restraints not constraints: each constraint *reduces* the parameter count by one. -- Ian > -----Original Message----- > From: owner-ccp4bb@jiscmail.ac.uk > [mailto:owner-ccp4bb@jiscmail.ac.uk] On Behalf Of Meyer, Peter > Sent: 14 February 2008 15:48 > To: CCP4BB@jiscmail.ac.uk > Subject: counting constraints? > > Hi, > > The recent discussion on Rwork/Rfree ratio reminded me of > something I was wondering about (*). When counting > constraints as observations for determining the observation > to parameter ratio, is each unique constraint counted, or > each time a given constraint is used. For example, if there > are 4 carbon oxygen bonds (assuming the same parameters, > let's say serine beta-carbon to serine gamma-oxygen), would > this count as 4 constraints as observations, or 1? > > Intuitively, it seems to me like it should be counting unique > constraints (although as near as I can tell these aren't > listed in refmac5 logfiles). But I don't have a clear > explanation for why, and of course I could be wrong on this. > > > Thanks, > > > Pete > > * Rough translation - I'm about to ask another stupid > question. Not like it's the first time. > > Disclaimer This communication is confidential and may contain privileged information intended solely for the named addressee(s). It may not be used or disclosed except for the purpose for which it has been sent. If you are not the intended recipient you must not review, use, disclose, copy, distribute or take any action in reliance upon it. If you have received this communication in error, please notify Astex Therapeutics Ltd by emailing I.Tickle@astex-therapeutics.com and destroy all copies of the message and any attached documents. Astex Therapeutics Ltd monitors, controls and protects all its messaging traffic in compliance with its corporate email policy. The Company accepts no liability or responsibility for any onward transmission or use of emails and attachments having left the Astex Therapeutics domain. Unless expressly stated, opinions in this message are those of the individual sender and not of Astex Therapeutics Ltd. The recipient should check this email and any attachments for the presence of computer viruses. Astex Therapeutics Ltd accepts no liability for damage caused by any virus transmitted by this email. E-mail is susceptible to data corruption, interception, unauthorized amendment, and tampering, Astex Therapeutics Ltd only send and receive e-mails on the basis that the Company is not liable for any such alteration or any consequences thereof. Astex Therapeutics Ltd., Registered in England at 436 Cambridge Science Park, Cambridge CB4 0QA under number 3751674 CCP4bb navigationCCP4bb <-- 2008 <-- February 2008 <-- 14 February 2008 |
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