Before we got HF apparatus in my group, we had a 4 year experience with
alternative cleavage techniques in combination with Boc-SPPS chemistry.
I'll try to summarise our impressions below.
1. If your peptide does not contain Cys, Met, Arg and providing His is
incorporated as Bom-derivative, you may safely and efficiently use
palladium(II) acetate with formic acid or other suitable hydrogen donor to
perform hydrodenolytic cleavage of peptide from PAM or Merrifield resins.
2. If your peptide contains M or/and C and does not contain R, the
"TMSOTfl-PhSMe-TFA system" introduced by Yajima et al will do the job
without problems. This approach will also work rather satisfactory in case
you have a single Arg(Tos) in the sequence. Arg(Mts) is a preferred
derivative in this case.
3. If you have 2 or more Arg residues in your peptide I do not reccomend to
use any cleavage technique other than liquid HF. Even in case BocArg(Mts)
has been employed throughout the SPPS.
The basic references and even protocols may be found in the latest
NovaBiochem catalogue.
Kindest regards,
Faithfully yours,
Igor Rodionov
Laboratory Of Peptide Chemistry
Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry
Pushchino, Moscow Region
142292, Russian Federation
E-mail: <rodionov@fibkh.serpukhov.su> or <Igor_Rodionov@iname.com>