PROTEOMICS FOR THE DIAGNOSIS OF DETERIORATION OF WALL PAINTINGS

PROTEOMICS FOR THE DIAGNOSIS OF DETERIORATION OF WALL PAINTINGS Gabriella Leo1, Piero Pucci1, Gennaro Marino1, Leila Birolo1. 1Dipartimento di Chimica Organica e Biochimica, Università di Napoli “Federico II”, Napoli, Italy. Ilaria Bonaduce2, Alessia Andreotti2, Maria Perla Colombini2. 2Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Italy. The pysico-chemical analysis of wall paintings is particularly challenging due to the vast range of inorganic and organic materials which often constitute them. Although the organic paint media can be often reliably identified, changes in the composition, degradation phenomena, the formation of minor components, and molecular modifications that have occurred as an effect of production processes and aging cannot be completely understood by using only gas chromatography/mass spectrometric based approaches. In these cases the support of other techniques able to give information also from the macromolecular composition point of view are often fundamental and, up to now, they have been used for limited number of cases. The application of proteomics strategy to the characterization of proteinaceous binders in paintings has been recently reported in the literature. Actually, these studies were dedicated to setting up a protocol to be used to identify proteinaceous paint media, and not focused to a better understanding of modifications and degradation phenomena undergone as an effect of processing treatments used by artists and restorers, as well as ageing. This paper presents a proteomic approach able to characterize the proteinaceous material and to evaluate the degradation pathway occurred to the wall painting. Particularly, a systematic analysis of samples from the 14th century frescoes of the Monumental Cemetery in Pisa indicates an extensive deamidation occurring on most of the peptides identified, suggesting that the miniature molecular clock, as Robinson and Robinson defined any amide residue present in peptides or proteins, might well be used as molecular marker in artworks. Deamidation, the major modification of casein and animal glue proteins present in the wall paintings, can be related to treatments undergone by the proteinaceous materials during the after war restoration, as well as due to aging effects induced by the microclimate of the Monumental Cemetery