Re: [ccp4bb] Off-topic Thrombin cleavage

2012-05-23 Thread Seema Nath
I have used both Novagen thrombin & lyophilized thrombin of BDBioscience(dissolved in 10X thrombin dilution buffer provided by Novagen) in both 'thrombin cleavge buffer' & others (HEPES pH 7.0, Bicine pH 9.0, MOPS pH 7.8) without adding calcium chloride - all the conditions permitted the cleavge

Re: [ccp4bb] DNA/RNA modeling

2012-05-23 Thread jens j birktoft
and if everything else fails including kicking the trash can one could indeed read the manual/FAQ - thanks Paul On Wed, May 23, 2012 at 4:27 PM, Paul Emsley wrote: > > On Wed, May 23, 2012 at 12:54 PM, Mark J van Raaij > wrote: > even more flexible than COOT? > - the only thing I can think of

[ccp4bb] Off-topic: probing hydrophobic surface with ANS

2012-05-23 Thread Huiming Li
Hi, Could someone refer me to some papers on using ANS to estimate amount of hydrophobic surface in a protein? I tried the classic way by STEP 1: titrating my protein into 1uM ANS till saturation to get the molar fluorescence activity of ANS, then STEP 2: titrate ANS into protein to get

Re: [ccp4bb] DNA/RNA modeling

2012-05-23 Thread Paul Emsley
On Wed, May 23, 2012 at 12:54 PM, Mark J van Raaij mailto:mjvanra...@cnb.csic.es>> wrote: even more flexible than COOT? - the only thing I can think of that I haven't worked out how to do in COOT is grabbing and moving one atom at a time. On 23/05/12 19:50, jens j birktoft wrote: Thanks Ma

[ccp4bb] Off topic: Complexes cloning

2012-05-23 Thread Theresa Hsu
Dear all A off-topic question - is there a practical limit for overexpression of membrane protein complexes (about 200 kDa in total)? This includes chaperones and my target proteins. Can I amplify the gene cluster and simply clone into a plasmid? Thank you.

Re: [ccp4bb] Off-topic Thrombin cleavage

2012-05-23 Thread Debasish Chattopadhyay
Thrombin works pretty good without any added calcium. We routinely added thrombin to whatever buffer the protein is in provided it doesn't have a lot of DTT. Some beta-mercaptoethanol is alright. What is the source of your thrombin? -Original Message- From: CCP4 bulletin board [mai

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Nikolaos Glykos
Hi Pete, I'm curious - which programs have you used for maximum-entropy for map calculation? Thanks, I thought no-one would ask :-) http://utopia.duth.gr/~glykos/graphent.html Don't download the program today. Or tomorrow. This coming weekend there will be a new release which w

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread George Sheldrick
In SHELXL. a refinement program sometimes used by small molecule crystallographers, all Fourier map for at least the last 20 years were weighted by Ic^2/(Ic^2+sigma^2(I)), where Ic is the calculated squared structure factor and sigma(I) is the square root of 1/w. w is the weight assigned to a r

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Nikolaos Glykos
Hi Ed, I am not sure I understand this - perhaps we are talking about different things. Even if by inversion procedure you mean simple calculation of (2fo-fc)*exp(i*phi), the fc is still technically a product of the refinement, which unless based on trivial least square target (i.e. no weig

Re: [ccp4bb] crystallization analysis software

2012-05-23 Thread Prince, D Bryan
Ed, I looked into this a number of years ago, and remember the following papers. I did not actually use any of the databases described due to IT issues at the time. I hope this helps. Kind regards, Bryan LISA: an intranet-based flexible database for protein crystallography project management

Re: [ccp4bb] DNA/RNA modeling

2012-05-23 Thread Francis E Reyes
For the RNA I recommend Eric Westhof's Assemble. F On May 23, 2012, at 9:32 AM, jens j birktoft wrote: > Hi everybody, > > Does anyone know of a (non-commercial) software that are suitable for > modeling DNA/RNA structures. Coot is great, however I am looking something > that allows more f

[ccp4bb] Off-topic Thrombin cleavage

2012-05-23 Thread Yuri Pompeu
Dear community, I am trying to cleave a hexaHis tag from my protein prior to crystallization. As I was setting up my digestion, my protein started to precipitate as soon as I added the recommended thrombin buffer. My question is, if anyone has encountered this, how well does it cleave without thr

Re: [ccp4bb] DNA/RNA modeling

2012-05-23 Thread Tuhin Bhowmick
Hi Jens, You can try NAMOT (Nucleic Acid MOdelling Tool), from the links below. http://namot.sourceforge.net/ http://sourceforge.net/projects/namot/ Best, Tuhin. Tuhin Bhowmick Prof. S. Ramakumar’s Lab Biocrystallography and Computation Department of Physics Indian Institute of Science Bangalor

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Dale Tronrud
On 05/23/12 08:06, Nicholas M Glykos wrote: > Hi Ed, > > >> I may be wrong here (and please by all means correct me), but I think >> it's not entirely true that experimental errors are not used in modern >> map calculation algorithm. At the very least, the 2mFo-DFc maps are >> calibrated to the

Re: [ccp4bb] DNA/RNA modeling

2012-05-23 Thread Francisco Hernandez-Guzman
Hi Jens, You can try the free DS Visualizer: http://accelrys.com/products/discovery-studio/visualization-download.php It comes with a free molecular builder for proteins, dna/rna and ligands. Please note that if you do need to make anything more interesting (energy calculations, minimizations,

[ccp4bb] DNA/RNA modeling

2012-05-23 Thread jens j birktoft
Hi everybody, Does anyone know of a (non-commercial) software that are suitable for modeling DNA/RNA structures. Coot is great, however I am looking something that allows more flexibility Thanks -- Jens J. Birktoft e-mail: jens.birkt...@nyu.edu slow-mail: 350 Central Park West, Suite 9F, N

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Francisco Hernandez-Guzman
I just wanted to take a moment to thank all of the respondents to the post. Indeed, my question was more practical in nature since I wanted to "see" the density around the ligand in question. From the first suggestions, I quickly did manage to generate the maps and accomplish my goal (special th

[ccp4bb] crystallization analysis software

2012-05-23 Thread Ed Pozharski
Does anyone know of a (non-commercial) software that can analyze results of a crystallization screen? What I am looking for is some way to tell what components/factors favor protein solubility/precipitation based on binary input (clear drop/precipitate). I did some googling, but please feel free

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Ed Pozharski
On Wed, 2012-05-23 at 18:06 +0300, Nicholas M Glykos wrote: > It seems that although you are not doubting the importance of maximum > likelihood for refinement, you do seem to doubt the importance of > closely > related probabilistic methods (such as maximum entropy methods) for > map > calculat

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Ed Pozharski
On Wed, 2012-05-23 at 18:06 +0300, Nicholas M Glykos wrote: > This is an amplitude modification. It does not change the fact that > the > sigmas are not being used in the inversion procedure Nicholas, I am not sure I understand this - perhaps we are talking about different things. Even if by i

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Ed Pozharski
On Wed, 2012-05-23 at 10:02 -0500, Pete Meyer wrote: > bviously > model and experimental errors do factor into calculation of a > 2mFo-DFc > map - but is weight and structure factor calculation part of map > calculation, or a distinct stage of data processing? Oh, I see. Sure, when the map co

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Pete Meyer
Nicholas, My experience from comparing conventional (FFT-based) and maximum-entropy- related maps is that the main source of differences between the two maps has more to do with missing data (especially low resolution overloaded reflections) and putative outliers (for difference Patterson maps

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Nicholas M Glykos
Hi Ed, > I may be wrong here (and please by all means correct me), but I think > it's not entirely true that experimental errors are not used in modern > map calculation algorithm. At the very least, the 2mFo-DFc maps are > calibrated to the model error (which can be ideologically seen as the >

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Pete Meyer
Ed, I may be wrong here (and please by all means correct me), but I think it's not entirely true that experimental errors are not used in modern map calculation algorithm. At the very least, the 2mFo-DFc maps are calibrated to the model error (which can be ideologically seen as the "error of ex

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Ed Pozharski
I may be wrong here (and please by all means correct me), but I think it's not entirely true that experimental errors are not used in modern map calculation algorithm. At the very least, the 2mFo-DFc maps are calibrated to the model error (which can be ideologically seen as the "error of experimen

Re: [ccp4bb] Calculating ED Maps from structure factor files with no sigma

2012-05-23 Thread Nicholas M Glykos
Hi Francisco, I'll play devil's advocate, but a measurement without an estimate of its error is closer to theology than to science. The fact that the standard deviations are not used for calculating an electron density map via FFT is only due to the hidden assumption that you have 100% complete