Re: [ccp4bb] protein turns brown

2010-09-27 Thread Guenter Fritz
Sandy, like mentioned previously, sounds like FeS. record an optical spectrum. Or even better, check whether there is somebody on the campus running an EPR machine (equipped for helium temperature measurements) Maybe a new FeS protein? FeS is not necessarily required as redox cofactor. It

[ccp4bb] protein turns brown

2010-09-24 Thread sandeep
Dear all, I have purified protein from E.coli. expression system. the protein has been purified with three independant columns. Now during concentration step using amicon, the protein shows brown colour. what could be the reason. best regards and Thanks, sandy

Re: [ccp4bb] protein turns brown

2010-09-24 Thread vikrant saa
September, 2010 2:04:54 PM Subject: [ccp4bb] protein turns brown Dear all, I have purified protein from E.coli. expression system. the protein has been purified with three independant columns. Now during concentration step using amicon, the protein shows brown colour. what could be the reason. best

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Ricardo de Pádua
Hi Sandy, Is there any possibility of your protein to contain an iron-sulfur cluster? Best Ricardo

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Andy Torelli
Hi Sandy, If your protein is soluble (i.e. we're not dealing with brown precipitate), it is possible that the brown color is due to a bound iron-sulfur cluster. In this case, your protein was always brown, but you couldn't see the color when it was very dilute. As a quick test, you could

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Van Den Berg, Bert
Maybe you should give us a hint about the identity of your protein (if you dare;-)). I'm sure there are folks around who may be able to say whether or not your protein is supposed to be brown. You can't expect too much help if you don't provide (m)any details. Cheers, Bert On 9/24/10

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Jürgen Bosch
[FeS] clluster ? Or some metal bound to your protein ? Is it dark brown or yellowish brown ? What's your protein concentration ? 25 mg/ml ? Jürgen - Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry Molecular Biology Johns Hopkins Malaria Research

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Matthew Bratkowski
It could be caused by iron contamination in one of your buffers. We used to buy glycerol in a metal canister and metal would leach into the glycerol. Because of this, one protein that I worked with would turn yellow, even at relatively low concentrations. I did not have this issue when using

[ccp4bb] Fw: [ccp4bb] protein turns brown

2010-09-24 Thread Ray Brown
From: Matthew Bratkowski mab...@cornell.edu To: CCP4BB@JISCMAIL.AC.UK Sent: Fri, September 24, 2010 11:38:14 AM Subject: Re: [ccp4bb] protein turns brown It could be caused by iron contamination in one of your buffers. We used to buy glycerol in a metal canister and metal would

Re: [ccp4bb] protein turns brown

2010-09-24 Thread MARTYN SYMMONS
Symmons Cambridge --- On Fri, 24/9/10, vikrant saa powervikr...@yahoo.co.in wrote: From: vikrant saa powervikr...@yahoo.co.in Subject: Re: [ccp4bb] protein turns brown To: CCP4BB@JISCMAIL.AC.UK Date: Friday, 24 September, 2010, 10:50 sometime it does happen becoz of protein aggregation

Re: [ccp4bb] protein turns brown

2010-09-24 Thread shiva bhowmik
toskgu...@rediffmail.com Subject: [ccp4bb] protein turns brown To: CCP4BB@JISCMAIL.AC.UK Date: Friday, September 24, 2010, 4:34 AM Dear all, I have purified protein from E.coli. expression system. the protein has been purified with three independant columns. Now during concentration step using

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Filip Van Petegem
I also have a similar observation for proteins purified by Ni-NTA column. After concentrating the sample eluted from the Ni-NTA column, I see a brownish-yellowish tinge closer to the bottom of the filter with colorless buffer on top. This is observed even for non-metal binding and non-FeS

Re: [ccp4bb] protein turns brown

2010-09-24 Thread shiva bhowmik
filip.vanpete...@gmail.com Subject: Re: [ccp4bb] protein turns brown To: CCP4BB@JISCMAIL.AC.UK Date: Friday, September 24, 2010, 2:50 PM I also have a similar observation for proteins purified by Ni-NTA column. After concentrating the sample eluted from the Ni-NTA column, I see a brownish-yellowish tinge

Re: [ccp4bb] protein turns brown

2010-09-24 Thread Daniel Bonsor
According to Pierce TCEP is more tolerant of nickel and cobalt. However, TCEP is inactivated by other metals, namely copper, magnesium, silver and zinc. Dan Daniel A. Bonsor, Boston Biomedical Research Institute, 64 Grove Street, Watertown, MA 02472 USA