Evaluation of the trifluoromethanosulfonic acid/trifluoroacetic acid/thioanisole cleavage procedure for application in solid-phase peptide synthesis.
As an extension of our investigation of peptidyl-resin linkage stability towards different cleavage procedures used in the solid-phase peptide synthesis (SPPS) technique, the present paper evaluated the trifluoromethanesulfonic acid (TFMSA)/trifluoroacetic acid (TFA)/thioanisole method, varying the type of resin (benzhydrylamine-resin, BHAR; methylbenzhydrylamine-resin, MBHAR and 4-(oxymethyl)-phenylacetamidomethyl-resin, PAMR) and peptide resin-bound residue (Gly and Phe). The vasoactive angiotensin II (AII, DRVYIHPF) and its [Gly8]-AII analogue linked to those resins used routinely in tert-butyloxycarbonyl (Boc)-SPPS chemistry were submitted comparatively to a time course study towards TFMSA/TFA cleavage. At 0 degrees C, [Gly8]-AII was completely removed from all resins in less than 6 h, but the hydrophobic Phe8 moiety-containing AII sequence was only partially cleaved (not more than 15%) from BHAR or MBHAR in this period. At 25 degrees C, [Gly8]-AII cleavage time decreased to less than 2 h irrespective of the solid support, and quantitative removal of AII from PAMR and MBHAR occurred in less than 3 h. However, about 10-15 h seemed to be necessary for cleavage of AII from BHAR, and in this extended cleavage reaction a significant increase in peptide degradation rate was observed. Regardless of the cleavage temperature used, the decreasing order of acid stability measured for resins was BHAR>MBHAR>PAMR. Collectively, these findings demonstrated the feasibility of applying TFMSA/TFA solution as a substitute for anhydrous HF at the cleavage step in Boc-SPPS methodology. Care should be taken however, as the cleavage efficacy depends on multiple factors including the resin, peptide sequence, the time and temperature of reaction.
Jubilut
G N
GN
Department of Biophysics, Universidade Federal de São Paulo, SP, Brazil.
Cilli
E M
EM
Tominaga
M
M
Miranda
A
A
Okada
Y
Y
Nakaie
C R
CR
D000596:Amino Acids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D010455:Peptides / Q000138:chemical synthesis*; D012116:Resins, Plant; D012997:Solvents; D013440:Sulfides / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry*; D014269:Trifluoroacetic Acid / Q000737:chemistry*
D000596:Amino Acids; D007202:Indicators and Reagents; D010455:Peptides; D012116:Resins, Plant; D012997:Solvents; D013440:Sulfides; D013451:Sulfonic Acids; C093850:methylphenylsulfide; D014269:Trifluoroacetic Acid