Re: Diferent recovery of Arg in sequences

L. Ericsson (ericsson@u.washington.edu)
Wed, 27 May 1998 09:28:30 -0700 (PDT)

When running amino acid analyses I have occasionally been surprised by a
somewhat low arginine value but the presence of ornithine. Ornithine can
come from "finger-prints" (therefore contaminated prep) but also from the
action of arginase on free arginine (The old "urea cycle"). I don't know
of any examples of an arginine residue in a protein being converted to
ornithine, but is it possible? Can ornithine substitue for arginine
during protein synthesis? If so, PTH-ornithine should not be very hard to
identify.
-Lowell Ericsson

On Wed, 27 May 1998, Katheryn Resing wrote:

> I have also had the experience of low recovery of arginine at one site, but
> not another. At the time, someone told me that arginine is limiting in
> bacterial expression systems and that you can get other amino acids in that
> position, as well as arginine precursors. It was supposed to be from one
> set of the arginine codons, but not the other and the problem that they had
> was fixed by changing the low recovery codon and enriching the medium for
> arginine. I never got references on it and if anyone out there knows them,
> I'd like to have them for my files.
>
> Katheryn Resing
>
>
>