Asp-Pro cleavage by H+

[Shaun D. Black]

Greetings,

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.


Sincerely,

Shaun Black

  =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
  = 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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