Asp-Pro cleavage by H+
Shaun D. Black
shaun at uthct.edu
Tue Jun 2 10:16:33 EST 1998
i.mcfarlane at icrf.icnet.uk (Ian McFarlane) wrote...
>Someone recently posted that the NH2-Asp-Pro-COOH bond was labile under
>acid conditions. Is this true for the NH2-Pro-Asp-COOH pair as well? Also
>does anyone have a protocol or set of reaction conditions that can be used
>to cleave the above peptide sequences?
The Pro-Asp bond is not especially acid labile (it cleaves with 6N HCl at
100 C for extended times like other peptide bonds). On the other hand,
and as you note, the Asp-Pro bond is significantly acid labile. A nice
protocol for cleavage of these linkages is found in "Methods of Protein
Microcharacterization" (J.E. Shively, ed; Humana Press 1986) in chapter
6 (G. Tarr) (see p. 167). Briefly, boil your sample in 0.1% TFA
(trifluoroacetic acid) under nitrogen for 30-40 min. This restricts
cleavage predominately to Asp-Pro bonds. Cool and put on HPLC directly
for peptide isolation.
I hope this proves useful to you.
= Shaun D. Black, PhD | Internet e-mail address: shaun at uthct.edu =
= Dept. of Biochemistry | University of Texas Health Center at Tyler =
= Tyler, TX 75710 | World Wide Web: http://psyche.uthct.edu =
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