Re: [ccp4bb] Off topic: insect cell expression
Hi, can you perform a thermal shift assay ? Google or it or find some references in a posting not too long ago perhaps 6 months or less. If so you can check your protein with various "additives" and see which ones stabilize your protein. What happens if you dialyse your sample instead of concentrating it to get rid of the imidazole ? Jürgen Daniel Jin wrote: Hi there, Sorry for the off topic questions. We need your feedback. We are expressing a rat protein in insect cells. It is expressed as a secreted protein with an N-terminal 6xHis tag. We can get about 4 mg of it from 1L culture and everything looked quite normal at the very beginning (at 4C). When I changed the buffer to HBS using centricon to get rid of imidazole (@ 4C), I noticed that it took a long time to concentrate and I saw some ppt. However, when I took some of it (at about 1.2 mg/ml) and kept them at room temperature, the solution turned cloudy in a few minutes. I tried to change the pH by diluted in 1M stock of different buffers (pH 4.5-8.5), change the NaCl concentration, and add 10% glycerol, but it still crashed out at RT. However, it seems OK, I hope, when kept on ice. I am wondering whether any of you had a similar experience before. It is not a problem for us to do everything at 4 degree. I just worry that it may indicate something wrong with this protein. The protein should be stable since it has been shaking at 27C for four days… Many thanks. Best, Chen__ -- Jürgen Bosch University of Washington Dept. of Biochemistry, K-426 1705 NE Pacific Street Seattle, WA 98195 Box 357742 Phone: +1-206-616-4510 FAX: +1-206-685-7002 Web: http://faculty.washington.edu/jbosch
Re: [ccp4bb] Off topic: insect cell expression
I would try the following: 1. Remove the His tag. 2. If you need to get rid of the imidazole I would try adding ammonium sulfate. 3. Is your protein proline- and/or rich in aromatic residues? This may explain your need for imidazole and solubility. > Hi there, > > Sorry for the off topic questions. We need your feedback. > > We are expressing a rat protein in insect cells. It is expressed as a > secreted protein with an N-terminal 6xHis tag. We can get about 4 mg of it > from 1L culture and everything looked quite normal at the very beginning > (at 4C). When I changed the buffer to HBS using centricon to get rid of > imidazole (@ 4C), I noticed that it took a long time to concentrate and I > saw some ppt. However, when I took some of it (at about 1.2 mg/ml) and > kept them at room temperature, the solution turned cloudy in a few > minutes. I tried to change the pH by diluted in 1M stock of different > buffers (pH 4.5-8.5), change the NaCl concentration, and add 10% glycerol, > but it still crashed out at RT. However, it seems OK, I hope, when > kept on ice. I am wondering whether any of you had a similar experience > before. It is not a problem for us to do everything at 4 degree. I just > worry that it may indicate something wrong with this protein. The protein > should be stable since it has > been shaking at 27C for four days > > Many thanks. > > Best, > Chen > > >
Re: [ccp4bb] Protein binding to Zn and Ca
Hi Neeraj, a couple of S100 proteins bind Zn2+ and Ca2+. Ca2+ binds to EF-hands; Zn2+ binds to specific sites distinct of the EF-hands. We are investigating Zn2+-binding by spectroscopy and crystallography. We think that Zn2+ is like Ca2+ a kind of second messenger. If you have questions, I am happy to discuss these things. Best, Guenter Hi all, I recently came across a question about an interesting idea. Does anyone know of an example of a protein binding to both Zn2+ and Ca2+ at the same time? Are there any known well studied precedents at all if any. Any help of insights would be very valuable. thanks, Neeraj -- *** Priv.Doz.Dr. Guenter Fritz Fachbereich Biologie Sektion Naturwissenschaften Universitaet Konstanz http://www.biologie.uni-konstanz.de/fritz Universitaetsstrasse 10 Postfach M665 D-78457 Konstanz e-mail: [EMAIL PROTECTED] Tel. Office: +49-(0)7531 88 3205 Tel. Lab : +49-(0)7531 88 3687 Fax: +49-(0)7531 88 2966
Re: [ccp4bb] birefringent spacegroups
Thank you Ian for the comment ! Apparently, I was a bit too quick in my answer. By the way, my mentioning of Fresnel's theory was of pure historical interest and not at all to say that the whole story was written at that time. I went back to my "Born & Wolf" (some kind of a bible in the optics field) and I am somewhat surprised of not seeing any comment on that topics. May be the comments exist, but implicitly in the cited litterature... Now, I am still wondering whether external "stresses" on biological crystals could indeed induce such unexpected birefringence. Philippe Dumas IBMC-CNRS, UPR9002 15, rue René Descartes 67084 Strasbourg cedex tel: +33 (0)3 88 41 70 02 [EMAIL PROTECTED] -Message d'origine- De : CCP4 bulletin board [mailto:[EMAIL PROTECTED] la part de Ian Tickle Envoyé : Thursday, June 12, 2008 9:20 PM À : CCP4BB@JISCMAIL.AC.UK Objet : Re: [ccp4bb] birefringent spacegroups But it seems that Hendrik Lorentz was the first to realise that symmetry breaking of the isotropy of the refractive index & other optical properties could occur in cubic crystals at sufficiently short wavelength even in the absence of a distorting force - the "spatial-dispersion-induced birefringence" effect referred to in the paper. Note that this is an intrinsic effect, it has nothing to do with external stress, electric field etc., and if you read the paper you'll see that such external effects were specifically eliminated as the cause of the observed effect. -- Ian > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Philippe DUMAS > Sent: 12 June 2008 19:20 > To: Ian Tickle; CCP4BB@JISCMAIL.AC.UK > Subject: RE: [ccp4bb] birefringent spacegroups > > Hello, > > A short comment of historical interest: the first theory about "double > refraction in crystals" (with explicit calculation of the > index ellipsoid) > goes back to 3 memoirs by A. Fresnel in 1821 and 1822. So, we > are even in > "older regions". > > This being said, in cubic crystals the index ellipsoid can > only be a sphere. > An so, no birefringence should exist (unless there is some > external cause of > anisotropy: mecanical stress, electric field,...). See Born & Wolff > (principles of optics) p. 703. May be, our "biological > crystals" might quite > easily develop such "stress birefringence"... > > Philippe Dumas > IBMC-CNRS, UPR9002 > 15, rue René Descartes 67084 Strasbourg cedex > tel: +33 (0)3 88 41 70 02 > [EMAIL PROTECTED] > > > > -Message d'origine- > De : CCP4 bulletin board [mailto:[EMAIL PROTECTED] la > part de Ian > Tickle > Envoyé : Thursday, June 12, 2008 7:19 PM > À : CCP4BB@JISCMAIL.AC.UK > Objet : Re: [ccp4bb] birefringent spacegroups > > > PS in case you missed it, here's the bottom line from the paper: > > "Interestingly, a cubic crystal has seven nonbirefringent > axes, four in > the <111> > directions and three in the <100> directions, with > birefringence maxima > in the twelve <110> directions." > > So it would appear that the optical properties of cubic crystals are > *more* complicated than those of lower symmetry systems, not > less! - and > previous conclusions about isotropy of cubic crystals probably arose > because the measurements were simply not precise enough (or > not carried > out at short enough wavelength) to detect the effect. However the > relevant theory goes back to Lorentz (1878) so it's not exactly new! > > Cheers > > -- Ian > > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Ian Tickle > > Sent: 12 June 2008 17:50 > > To: Ethan A Merritt; Jacob Keller > > Cc: CCP4BB@jiscmail.ac.uk > > Subject: RE: [ccp4bb] birefringent spacegroups > > > > Hi Ethan > > > > You could be right, see this paper: > > > > > http://physics.nist.gov/Divisions/Div842/Gp2/DUVMatChar/PDF/In > tBiref.pdf > > > > Cheers > > > > -- Ian > > > > > > > -Original Message- > > > From: [EMAIL PROTECTED] > > > [mailto:[EMAIL PROTECTED] On Behalf Of Ethan A Merritt > > > Sent: 12 June 2008 15:46 > > > To: Multiple recipients > > > Cc: CCP4BB@jiscmail.ac.uk > > > Subject: Re: [ccp4bb] birefringent spacegroups > > > > > > On Wednesday 11 June 2008 23:55, Robin Owen wrote: > > > > Hi Jacob, > > > > > > > > The birefringence of a crystal is determined by a three > > dimensional > > > > shape (the indicatrix) describing how refractive index > > varies with > > > > direction within the crystal. You can think of this as a 3d > > > ellipse and > > > > the birefringence is given by the difference in length of > > > the two axes > > > > of the ellipse 'seen' by light as it passes through the crystal. > > > > > > > > The orientation and shape of the indicatrix are constrained > > > by the point > > > > group symmetry of the crystal. In the case of cubic > crystals, the > > > > indicatrix is characterised by four 3-fold axes. The > > > indicatrix for all > > > > cubic crystals is thus a sphere and cubic crystals are > > > non-birefringent
Re: [ccp4bb] Density is not clear
Hi,John, I faced the similar situation before even the resolution about 2.4. At that region the residues are all hydrophobic ones and should be very flexible . Arp/warp and phenix do not work well and resolve does not improve the density either. At the end I just try to build the model as I can . That is all for me and hope someone can give us some good suggestions . Good luck! leo john kryst wrote: Hi all !! I am working with two data sets of same protein (130a/a) with resolutions 2.8 and 3.2 A. In both the cases the density for 100-130 aa is not very clear.. it forms couple of helices.. i can see a long tube going but it is feature less.. It is a MR solution.. i have tried TLS refinement with different TLS groups.. but no luck... i have also tried DM but not much improvement... Data looks clean without any twinning... R and Rfee are around 22.8 and 28.5 for both the structures... Any suggestions?? regards John
Re: [ccp4bb] Protein binding to Zn and Ca
Hi there. Clostridial Alpha toxins (phospholipase Cs that cause gas gangrene) bind 2-3x Zinc in the catalytic site, and 2-3 Ca in the membrane binding domain. See 1ca1, 1olp, 1qmd and others. Dave 2008/6/13 Neeraj Kapoor <[EMAIL PROTECTED]>: > Hi all, > I recently came across a question about an interesting idea. Does > anyone know of an example of a protein binding to both Zn2+ and Ca2+ at the > same time? Are there any known well studied precedents at all if any. Any > help of insights would be very valuable. > > thanks, > Neeraj > -- David C. Briggs PhD Father & Crystallographer http://www.dbriggs.talktalk.net AIM ID: dbassophile
Re: [ccp4bb] Arp/warp space group P 21 2 21
Dear Victor I'm glad that you see the desirability of updating Arp/warp to allow any setting. I'm a recent convert to this idea myself Best wishes Phil On 11 Jun 2008, at 09:17, [EMAIL PROTECTED] wrote: Thanks very much to everybody for useful discussion on space groups, axes and ARP/wARP. I would particularly refer to the argument on space group uncertainty in data processing and a need to have convenient means to screen various space groups and axes settings for, e.g. automated molecular replacement. Thanks again and best regards, Victor - This mail sent through IMP: http://horde.org/imp/
Re: [ccp4bb] birefringent spacegroups
> -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Ethan Merritt > Sent: 12 June 2008 19:41 > To: Multiple recipients > Cc: CCP4BB@jiscmail.ac.uk > Subject: Re: [ccp4bb] birefringent spacegroups > > But the ellipsoid is only a convenient approximation based on > properties > evaluated at 3 orthogonal axes. It is not a complete > description, it is > simple model. More complex models may describe more complex > properties, > as is the case in the paper that Ian refers to. > > If "birefringence" is formally defined in terms of the approximating > ellipsoid, this is correct. I do not know if this is the case or not. > But if birefringence is generalized to mean "optical index varies with > incident illumination vector" then I believe all protein crystals > are birefringent. > > I may be talking nonsense here. If so, I welcome the opportunity to > learn better. > > Ethan > No I think you're quite right, birefringence clearly refers to any case where the refractive index is anisotropic for any general pair of directions, not just in specific orthogonal directions. In any case the birefringent direction [110] in cubic is orthogonal to the non-birefringent direction [001] so the old definition is still applicable anyway. BTW here's a patent issued for a method to get around the problems in lithographic fabrication of semiconductors caused by optical elements made from birefringent cubic crystals, so it's a very real problem, not just one of theoretical interest! http://www.patentstorm.us/patents/6844972/fulltext.html Cheers -- Ian 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 [EMAIL PROTECTED] 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
Re: [ccp4bb] need test data set
The CCP4 courses page includes a variety of talks, tutorials and (most importantly!) photos from past events, see http://www.ccp4.ac.uk/ccp4course.php under "Some documentation of past events" In particular, I've put the MR tutorial from Oulu under the entry "BIOXHIT/BCO course on CCP4 structure determination pipeline" If any tutors from any event want me to add stuff, let me know. Martyn On Thu, 2008-06-12 at 14:30 +0100, Kevin Cowtan wrote: > The crank/dm/buccaneer tutorial is now available here: > http://www.ysbl.york.ac.uk/~cowtan/buccaneer/tutorial/tutorial.html > > More data is available in your $CEXAM directory. There are datasets for > RNAse and toxd dataset - both SIR/MIR. In the CVS version there is also > SIRAS data for rnase and a Gere dataset - see > http://www.ccp4.ac.uk/ccp4bin/viewcvs/ccp4/examples/. > > Beyond that, the JCSG is probably the place to go. > > Jayashankar wrote: > > Dear scientists and friends, > > > > I am much interested to learn things by my own. > > There are many guys out there as me. > > To fulfill the thirst and quest for more crystallographic practical > > knowledge, I need test data set for > > SAD,MAD,SIR,MIR,SIRAS,MIRAS. > > > > And I want to remind kevin and Martyn that they told they will give link > > for the test dataset to play with most of the ccp4 programs in the wiki. > > (during recent bioxhit ,oulu workshop) > > where can i get them, is there any scientist ready to provide. > > > > -- > > S.Jayashankar > > Research Student > > Institute for Biophysical Chemistry > > Hannover Medical School > > Germany -- *** * * * Dr. Martyn Winn * * * * STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD, U.K. * * Tel: +44 1925 603455E-mail: [EMAIL PROTECTED] * * Fax: +44 1925 603825Skype name: martyn.winn * * URL: http://www.ccp4.ac.uk/martyn/ * ***
Re: [ccp4bb] birefringent spacegroups
PS I found a nice presentation from the NIST group explaining the theory behind the cubic birefringence effect: http://math.nist.gov/mcsd/Seminars/2004/2004-06-10-shirley-presentation. pdf . Slide 33 has some nice graphics summarising the birefringence effect in all crystal systems. -- Ian > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Ian Tickle > Sent: 13 June 2008 11:20 > To: Ethan Merritt > Cc: CCP4BB@jiscmail.ac.uk > Subject: RE: [ccp4bb] birefringent spacegroups > > > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Ethan Merritt > > Sent: 12 June 2008 19:41 > > To: Multiple recipients > > Cc: CCP4BB@jiscmail.ac.uk > > Subject: Re: [ccp4bb] birefringent spacegroups > > > > But the ellipsoid is only a convenient approximation based on > > properties > > evaluated at 3 orthogonal axes. It is not a complete > > description, it is > > simple model. More complex models may describe more complex > > properties, > > as is the case in the paper that Ian refers to. > > > > If "birefringence" is formally defined in terms of the > approximating > > ellipsoid, this is correct. I do not know if this is the > case or not. > > But if birefringence is generalized to mean "optical index > varies with > > incident illumination vector" then I believe all protein crystals > > are birefringent. > > > > I may be talking nonsense here. If so, I welcome the opportunity to > > learn better. > > > > Ethan > > > > No I think you're quite right, birefringence clearly refers > to any case > where the refractive index is anisotropic for any general pair of > directions, not just in specific orthogonal directions. In > any case the > birefringent direction [110] in cubic is orthogonal to the > non-birefringent direction [001] so the old definition is still > applicable anyway. BTW here's a patent issued for a method to get > around the problems in lithographic fabrication of > semiconductors caused > by optical elements made from birefringent cubic crystals, so it's a > very real problem, not just one of theoretical interest! > > http://www.patentstorm.us/patents/6844972/fulltext.html > > Cheers > > -- Ian > > > 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 [EMAIL PROTECTED] 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 > > 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 [EMAIL PROTECTED] 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 suscept
[ccp4bb] Off topic? [was: 2 Job Post at IRB Barcelona]
Dear list members, Sorry to bother you with a personal reflection that somehow asked for a way out of my mind after the umpteenth announcement of this kind. Please, no bad feelings for that post, no more than for any other of its kind, anyway. As it often happens, my reflection takes the form of a question: has anybody else noticed that it is becoming more and more common to see job ads in our field where the duties of the candidate are ( rather ) well established, but not their rights, let alone the type of contract that is offered? Or perhaps because being myself looking for a job I have become hyper-sensitive? To clarify, I come from a working-class family, I'm used to these ads when it comes to the so-called 'non-qualified jobs'. I'm not really willing to open a debate, most likely prone to be a futile one, I just wanted to raise the question on other minds. Thanks for your patience! Miguel -- http://www.pangea.org/mol/spip.php?rubrique2 ~~~ Je suis de la mauvaise herbe, Braves gens, braves gens, Je pousse en liberté Dans les jardins mal fréquentés! Georges Brassens
[ccp4bb] High Salt Sample
G'day, Given my newbie status (and paucity of material on the subject), would everybody be so kind as to share their experiences with crystallization of high salt protein samples (I'm thinking 0.3M NaCl or greater). n.b. googling "salting out protein crystal" gives a year 2000 summary posting, but there must be more examples now Cheers, Randy _ Instantly invite friends from Facebook and other social networks to join you on Windows Live™ Messenger. https://www.invite2messenger.net/im/?source=TXT_EML_WLH_InviteFriends
[ccp4bb] Cool - Clipper installation
Dear All I had installed coot on my red hat system. For some reason it has been deleted. I'm trying to install again. Before that Do I need to install "clipper". When I'm trying to install clipper it says error message like --- configure: error: If fftw exist on you system, are you sure you are using the fftw libraries that was configured with --enable-float? --- I do not know the real problem. Can some one suggest me? Thankz Sajid Meet people who discuss and share your passions. Go to http://in.promos.yahoo.com/groups/bestofyahoo/
Re: [ccp4bb] Coot - Clipper installation
You shouldn't be trying to install clipper or fftw. If you use the precompiled coot binaries, then you get precompiled clipper and fftw as part of the package. If you want to build it yourself (not recommended except for experts), you should use one of the autobuild scripts which will download and build clipper, fftw, and all the other depedencies for you. See... http://www.ysbl.york.ac.uk/~emsley/coot/coot-faq.html sajid akthar wrote: Dear All I had installed coot on my red hat system. For some reason it has been deleted. I'm trying to install again. Before that Do I need to install "clipper". When I'm trying to install clipper it says error message like --- configure: error: If fftw exist on you system, are you sure you are using the fftw libraries that was configured with --enable-float? --- I do not know the real problem. Can some one suggest me? Thankz Sajid Meet people who discuss and share your passions. Go to http://in.promos.yahoo.com/groups/bestofyahoo/
Re: [ccp4bb] need test data set
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hello; Indeed you might also be interested in giving a look at Depot : http://xtal.nki.nl/Depot This is the place we're asking xtalographers to deposit some experimental data for helping the development of ARP/wARP. Every-time the depositor is OK with it we make the data available to others. I'm not completely sure what you mean by "test data set for SAD,MAD,SIR,MIR,SIRAS,MIRAS". Do you mean the actual Fs from the different derivative/wavelength, or do you mean the phases estimated from the experiment (and before any density modification, model refiinement...) ? If what you request is the latter, then this is what is available on Depot. Do not hesitate to mail me directly if you have any difficulty with the web pages I'm mentioning here. Cordially; Serge. Le 12 juin 08 à 14:40, Jayashankar a écrit : Dear scientists and friends, I am much interested to learn things by my own. There are many guys out there as me. To fulfill the thirst and quest for more crystallographic practical knowledge, I need test data set for SAD,MAD,SIR,MIR,SIRAS,MIRAS. And I want to remind kevin and Martyn that they told they will give link for the test dataset to play with most of the ccp4 programs in the wiki. (during recent bioxhit ,oulu workshop) where can i get them, is there any scientist ready to provide. *** Dr. Serge COHEN GPG Key ID: 0B5CDAEC N.K.I. Department of Molecular Carcinogenesis (B8) Plesmanlaan 121 1066 CX Amsterdam; NL E-Mail: [EMAIL PROTECTED] Tel : +31 20 512 2053 *** -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.8 (Darwin) iEYEARECAAYFAkhSskUACgkQlz6UVQtc2uxxtACg5gNQqRvX77LNVDKDEVoxQtzZ Z6YAoNHqnzCAahZUvlMWNtAceekOhUaY =Cjmi -END PGP SIGNATURE-
Re: [ccp4bb] Off topic? [was: 2 Job Post at IRB Barcelona]
I just graduated, but I didn't look very hard for experimental crystallography positions, so I can't comment on job ads. Still, I live in Berkeley, which gives me plenty of perspective on the state of the field. Two thoughts: 1. Many universities would prefer not to hire many tenured professors if possible. They're expensive, and tenure is annoying. This is true even at the richest US institutions, so I assume it's true internationally as well. 2. Crystallographers aren't exactly becoming obsolete, but the field of structural biology will continue to expand without an increase in the number of full-time (PhD-holding) crystallographers. Everyone needs to have experts around for the really tough problems, but I don't see much need for entire labs devoted solely to crystallography in the future. We're all going to be replaced by robots anyway. (More importantly, every other technique has become more accessible too, so there's no excuse for a crystallographer not to do follow-up experiments if he or she has the opportunity. Which is why both of our former P.I.s ended up publishing results from work in biosafety facilities in addition to crystal structures; and Jean Pieters' PknG structure is a good example from the other direction..) I did in fact spend all of grad school working exclusively on crystallography problems, which may have been unwise; fortunately, I'm also good enough with computers to have plenty of options. I didn't even bother looking for industry jobs; there are still a few available, but I've seen far more qualified people than I turned down. On Fri, Jun 13, 2008 at 6:40 AM, Miguel Ortiz-Lombardía <[EMAIL PROTECTED]> wrote: > Dear list members, > > Sorry to bother you with a personal reflection that somehow asked for a way > out of my mind after the umpteenth announcement of this kind. Please, no bad > feelings for that post, no more than for any other of its kind, anyway. > > As it often happens, my reflection takes the form of a question: has > anybody else noticed that it is becoming more and more common to see job ads > in our field where the duties of the candidate are ( rather ) well > established, but not their rights, let alone the type of contract that is > offered? > > Or perhaps because being myself looking for a job I have become > hyper-sensitive? To clarify, I come from a working-class family, I'm used to > these ads when it comes to the so-called 'non-qualified jobs'. > > I'm not really willing to open a debate, most likely prone to be a futile > one, I just wanted to raise the question on other minds. > > Thanks for your patience! > > > Miguel > -- > http://www.pangea.org/mol/spip.php?rubrique2 > ~~~ > Je suis de la mauvaise herbe, > Braves gens, braves gens, > Je pousse en liberté > Dans les jardins mal fréquentés! > Georges Brassens
Re: [ccp4bb] Protein binding to Zn and Ca
Concanavalin A can be made to bind Zn and Ca. Its binding site has room for one transition metal and one alkaline earth metal. http://www.jbc.org/cgi/content/abstract/271/27/16144 Highly recommended reading material on one of the classical protein targets Sumner's Nobel Prize lecture is here http://nobelprize.org/nobel_prizes/chemistry/laureates/1946/sumner-lecture.p df) Artem -Original Message- From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Neeraj Kapoor Sent: Thursday, June 12, 2008 11:15 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Protein binding to Zn and Ca Hi all, I recently came across a question about an interesting idea. Does anyone know of an example of a protein binding to both Zn2+ and Ca2+ at the same time? Are there any known well studied precedents at all if any. Any help of insights would be very valuable. thanks, Neeraj
