RE: Protein sequencing: retention time of oxidized methionine

Fowler, Audree (AFowler@mednet.ucla.edu)
Mon, 11 Jan 1999 08:12:08 -0800

Well, I see all this about CNBr and I had to give my thoughts about this
even though I will retire at the end of June. I will not disappear then
but my hair is so white now that it is time but I will be around.
Anyhow , as a few of you know long ago but not far away we sequenced
beta galactosidase. The older dogma was that Met-Thr and Met-Ser
sequences were not cleaved (Schroeder 1962). We did not see that in beta
gal. The cleavage was really complete. The only problem was the acid
splitting at Asp-Pro (there are 3 in beta gal).
As far as Met sulfoxide we do see a peak at around Thr even though we
have DTT in the Ethyl Acetate.
I will see you all in March but don't expect me to disappear
Audree Fowler

> -----Original Message-----
> From: Carol Beach [SMTP:cmbeach@pop.uky.edu]
> Sent: Monday, January 11, 1999 5:32 AM
> To: Recipients of ABRF List
> Subject: Re: Protein sequencing: retention time of oxidized
> methionine
>
> At 09:59 AM 1/11/99 +0000, Len Packman wrote:
> >Deb
> >
> >Met-Thr bonds are resistant to CNBr cleavage, so this will contribute
> to
> >incomplete cleavage patterns, depending on the frequency of
> occurrence in
> >the sequence.
> >
> >Len
> >
>
> Deb:
> Want to read more about this? Check out "Enhancement of
> Cyanogen
> Bromide Cleavage Yields for Methionyl-Serine and Methionyl-Threonine
> Peptide
> Bonds" by Raymond Kaiser and Lorraine Metzka in Analytical
> Biochemistry 266,
> 1-8 (1999). The article includes nifty chemical reaction schemes.
>
> Carol
>
>
> Carol Manley Beach, Ph.D.
> Protein Sequence Analysis
> Macromolecular Structure Analysis Facility
> 232 Combs Cancer Research Building
> University of Kentucky
> Lexington, KY 40536-0096
>
> cmbeach@pop.uky.edu
> (606)257-4932 (office)
> (606)257-4475 (lab)
> (606)323-3909 (FAX)