Amino acid analysis results

John E. Fox altabios at
Wed Sep 20 07:36:33 EST 1995

In article <reedan-1909951419510001 at>, reedan at (Daniela Sciaky) says:
>We had a protein expressed in a pET vector with the his tag at the C
>terminus. Amino acid analysis shows that the amount of each amino acid is
>as expected for cysteine. We don't understand what would account for the
>lack of cysteines. Is cysteine particularly labile?

Yes Cys is often lost during hydrolysis, the recovery is very
The best way would be to convert the cys to cysteic acid and 

John Fox

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