Investigation of proteins in samples of a mid-18th century colonial mural painting by MALDI-TOF/MS and LC-ESI/MS (Orbitrap)

LEVY, IVANA K.; NEME TAUIL, RICARDO; VALACCO, MARIA P.; MORENO, SILVIA; SIRACUSANO, GABRIELA; MAIER, MARTA S.

MICROCHEMICAL JOURNAL

ELSEVIER SCIENCE BV

Año: 2018 vol. 143 p. 457 - 466

0026-265X

In this paper, we report the study of proteinaceous binders in samples from a South American Colonial 18thcentury painting using two complementary mass spectrometry techniques. Before restoration, seven microsamples were extracted from representative colors of one of the mural paintings located inside the church of OurLady of Copacabana de Andamarca built in 1723 in Bolivia. Previous analysis by gas chromatography (GC) of theamino acid derivatives of the extracted protein fraction of three of the samples, suggested the presence of animalglue and egg. In this work, we introduce a methodology that combines a protein extraction procedure with atypical treatment for analysis of proteins as tryptic peptides by mass spectrometry. For this study, we applied inthe first stage, MALDI-TOF/MS and then, LC-ESI/MS (Orbitrap), an ultrahigh resolution mass spectrometry, toachieve more reliability in the identification of the protein binders.By LC-ESI/MS (Orbitrap), we detected several peptides from egg white proteins, particularly ovalbumin, ovotransferrin and lysozyme, and egg yolk proteins, vitellogenin-2 and apolipoprotein B, with high confidencepeptides each. In all the samples, the presence of collagen from animal provenance was established by MALDITOF/MS and LC-ESI/MS (Orbitrap).To our knowledge, this is the first time that protein binders in Andean paintings are identified without ambiguityby MALDI-TOF/MS and LC-ESI/MS (Orbitrap) mass spectrometry using a proteomic approach.