Free Sulfhydryl detection

Revati Tatake rtatake at
Tue Mar 19 21:53:35 EST 1996

In article <4ibu6n$doi at>, Michael Daws <Michael.Daws at> 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? 
>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 

Good Luck.



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