In article <4ibu6n$doi at studium.student.umu.se>, Michael Daws <Michael.Daws at ucmp.umu.se> writes:
>I have a 19-mer peptide (2200 MW) with a C-terminal cysteine which I
>purchased and received as a lyophilised powder. The company told me
>that the peptide would be greater than 95% monomer, however the results
>I have been getting would suggest that the majority of the peptide is
>disulphide bonded. Is there any nice easy colorimetric reagent I can
>use to detect free sulphydryl groups so that I can determine just how
>much of my peptide is disulphide bonded? Alternatively does anybody
>know a recipe for a gel that I could use to detect such a difference?
>Thanks.
>>Mike Daws
>
Try using Ellman's reagent, which reacts with free SH groups. It gives
orange color and can be quantitated colorimetrically. It is available from
Sigma/Aldrich.
Good Luck.
Jay.
>
