In situ neutralization in Boc-chemistry solid phase peptide synthesis. Rapid, high yield assembly of difficult sequences.
Int J Pept Protein Res
; 40(3-4): 180-93, 1992.
Article
in En
| MEDLINE
| ID: mdl-1478777
ABSTRACT
Simple, effective protocols have been developed for manual and machine-assisted Boc-chemistry solid phase peptide synthesis on polystyrene resins. These use in situ neutralization [i.e. neutralization simultaneous with coupling], high concentrations (> 0.2 M) of Boc-amino acid-OBt esters plus base for rapid coupling, 100% TFA for rapid Boc group removal, and a single short (30 s) DMF flow wash between deprotection/coupling and between coupling/deprotection. Single 10 min coupling times were used throughout. Overall cycle times were 15 min for manual and 19 min for machine-assisted synthesis (75 residues per day). No racemization was detected in the base-catalyzed coupling step. Several side reactions were studied, and eliminated. These included pyrrolidonecarboxylic acid formation from Gln in hot TFA-DMF; chain-termination by reaction with excess HBTU; and, chain termination by acetylation (from HOAc in commercial Boc-amino acids). The in situ neutralization protocols gave a significant increase in the efficiency of chain assembly, especially for "difficult" sequences arising from sequence-dependent peptide chain aggregation in standard (neutralization prior to coupling) Boc-chemistry SPPS protocols or in Fmoc-chemistry SPPS. Reported syntheses include HIV-1 protease(1-50,Cys.amide), HIV-1 protease(53-99), and the full length HIV-1 protease(1-99).
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Peptides
/
Polystyrenes
/
Resins, Synthetic
/
Formic Acid Esters
Language:
En
Journal:
Int J Pept Protein Res
Year:
1992
Document type:
Article
Affiliation country:
Canada