Infrared study of trifluoroacetic acid unpurified synthetic peptides in aqueous solution: Trifluoroacetic acid removal and band assignment

LAURA E. VALENTI; MAXIMILIANO BURGOS PACI; CARLOS P. DE PAULI; CARLA E. GAICOMELLI

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2011 vol. 410 p. 118 - 118

ynthetic peptide or protein samples are mostly unpurified with trifluoroacetic acid (TFA) used during the synthesis procedure, which strongly interferes with structure determination by infrared (IR) spectros- copy. The aim of this work was to propose a simple strategy to remove TFA contribution from attenuated total reflection (ATR)–IR spectra of the hexahistidine peptide (His6) in aqueous solution to study the con- formation of this synthetic peptide without previous purification. Such a strategy is based on the subtrac- tion mode widely employed to remove water contribution, and it is tested with TFA unpurified histidine as a model system. The subtraction is based on eliminating the strong TFA bands at 1147 and 1200 cm1 by applying a scaling factor (as in buffer correction). The proposed modes represent excellent strategies that do not modify spectral features, and they provide reliable routines to obtain the synthetic peptide spectrum without