Hi everyone, the in situ iodination reaction described in the following classic paper by the late Paul Sigler works quite well.
Iodination of a single tyrosine in crystals of alpha-chymotrypsin. Sigler PB. Biochemistry. 1970 Sep 1;9(18):3609-17. The primary purpose of my experiment (which took place 11 years ago according to my notebook) was indeed to iodinate tyrosines, but difference fourier analysis using calculated phases from the final refined MIR structure to reveal the complete iodination model (out of curiosity), showed that in addition to iodination of two tyrosines, two histidines had also been iodinated! In retrospect, I had actually run across those peaks in my cross-difference fourier maps but thought that they were too 'secondary' to be included in the heavy atom model. Best wishes Savas ---- Savvas Savvides L-ProBE, Unit for Structural Biology Ghent University K.L. Ledeganckstraat 35 9000 Ghent, BELGIUM office: +32-(0)9-264.51.24 ; mobile: +32-(0)472-92.85.19 Email: savvas.savvi...@ugent.be http://www.lprobe.ugent.be/xray.html -----Original Message----- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Alessandro Vannini Sent: Tuesday, March 31, 2009 9:11 PM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Halide soaking Hi, it worked very nice for me in 1 out of 1 case where I tried it :-). Very well diffracting crystals (1.8 Ang), rather small protein 20 kDa, 50 %solvent content, 1 mol/ASU. 20-30 s soak in 0.5 M NaBr resulted in 6 nice ordered sites. It was crucial for us to collect a 3 wavelength MAD data set. A SAD data set (using just the peak, even if with high redundancy ) was not enough to obtain traceable electron density map, even-though one could distinguish clearly protein boundaries and solvent channels. Good luck Ale On 31 Mar 2009, at 18:19, tat cheung cheng wrote: > Hi all > > I am now trying to do bromide soaking, but i am not really sure does > the bromide atom enter my crystal. So is there any signs that > indicate the entry of bromide atom? e.g. does the space group, cell > dimension change? or just nothing change, and the bromide atom just > get in? > Thanks very much. > > T.C. Cheng > > > Yahoo!香港提供�W上安全攻略，教你如何防��黑客! ��前往 http://hk.pro > mo.yahoo.com/security/ 了解更多! E-mail message checked by Spyware Doctor (6.0.0.386) Database version: 5.12080 http://www.pctools.com/en/spyware-doctor-antivirus/
