Re: PEPSYN: n-terminal formylation
benoiton@aix1.uottawa.ca
Wed, 17 Sep 1997 10:10:34 -0400 (EDT)
1. The formyl group will NOT be stable to trifluoroacetic acid.
2. When you couple N-formyl-methionine, the danger of racemization does
exist, since it is an acylamino acid and not an alkoxycarbonylamino
acid. I suggest you avoid the use of 'onium'-type coupling reagents where
the milieu is swamped with tertiary amine. Best option is probably good
old carbodiimide with some HOBt for good measure.
3. If you have to use Tfa to cleave the chain from the resin, then you
might as well use Boc-Methionine, deprotect and cleave off at once,
then acylate with the succinimidyl ester of formic acid. Now, I don't know
offhand if you can buy this. Also, its applicability presumes you don't
have a lysyl residue in your peptide.
I leave you with this for now.
Leo Benoiton
benoiton@aix.uottawa.ca
On Tue, 16 Sep 1997 Haaseth@brcf.med.umich.edu wrote:
> Dear esteemed colleagues:
>
> Can anyone please give me advice about synthesizing a peptide
> with an N-formyl methionine on the N-terminus? Specifically,
> after I attach N-formyl methionine (available from Sigma) is the
> formyl group stable to TFA cleavage? Any other hints about work-up
> and purification?
>
> Thanks in advance for any help or suggestions.
>
> Ron Haaseth
> Univeristy of Michigan
>
>