Re: [ccp4bb] Protein Color

- Protein crystallography

Main steps:

- Protein purification
- Crystallisation

Special:

- Programs for crystallography
- X-ray detectors

Basic tutorials:

   - Chemistry
   - Protein
   - Peptide
   - Amino Acids

Xtal community:

- CCP4BB

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: CNS refinement problem
From: jxqi jxqi {- at -} MAIL {- dot -} IM {- dot -} AC {- dot -} CN
Date: 2008-09-06

Next message:
Subject: Re: Protein Color
From: Filip Van Petegem filip {- dot -} vanpetegem {- at -} GMAIL {- dot -} COM
Date: 2008-09-06

Subject: Re: Protein Color
From: Joe Cockburn cockburn {- at -} PASTEUR {- dot -} FR
Date: 2008-09-06

Hi Matt,
I sometimes see a similar thing with my proteins, which definitely don't
possess metal co-factors or prosthetic groups. I found that gel filtration
got rid of it - the browny-yellow stuff came out in the void fraction so I
figured it was aggregated protein. I think it was aggregation via the
his-tags around traces of copper in my sample, which could explain the
brown-ish colour.
What happens if you concentrate the protein in the presence of EDTA?
Joe

> Hello.
>
> I am working with a protein that turns a yellowish-brown color when it is
> concentrated to around 2 mg/ml or higher in a small volume (a few hundred
> uL). I was wondering if the protein bound a metal or other prosthetic
> group that would give it this color? The protein's color somewhat
> resembles iron binding proteins, but there is no peak in the 400 nm range
> that would suggest heme, and an iron sulfur cluster is not that likely
> since there are only five cysteines in the protein. Proteins with
> structures homologous to the one I am studying bind magnesium, but are not
> know to bind other metals. Any information about what this color might
> suggest about the protein or how I could analyze possible bound metals or
> prosthetic groups using only a small amount of protein would be helpful.
>
> Matt
>

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: CNS refinement problem
From: jxqi jxqi {- at -} MAIL {- dot -} IM {- dot -} AC {- dot -} CN
Date: 2008-09-06

Next message:
Subject: Re: Protein Color
From: Filip Van Petegem filip {- dot -} vanpetegem {- at -} GMAIL {- dot -} COM
Date: 2008-09-06