Francesca Galluzzi (UBx)

Objectives

(i) identification of proteins in paint binders and their biological origins for a better understanding of artworks

(ii) identification of protein chemical modifications (due to local environment, pollution, restoration treatments, conservation conditions, etc.) for a better knowledge of artwork conservation/degradation.

Expected Results

The impact of commonly used restoration tools will be defined at molecular level. Proteins truncations and chemical modifications will be determined. Identification of common and uncommon protein modifications, identification of biological species, study of proteins from unsequenced genomes will be massively improved.

My project

The study of paintings consists of identifying pigments and binders to highlight the techniques used by the artists but also to propose the most appropriate conservation conditions and restoration treatments. Throughout the past centuries, artists have used a wide range of natural components to find the best painting recipes and formulation. The interaction between the different compounds (pigment particles and organic molecules) ensures the cohesion of the paint layer and its adhesion to the support, but often it is also associated to degradation mechanisms resulting from natural ageing or inappropriate conservation/restoration conditions of artworks. Among binders used for artworks, proteins represent a key molecule and proteomics emerged recently as the most informative technique to study proteins in figurative art. In this thematic section, both bottom up and top down proteomics will be used to study protein-based materials starting with their accurate identifications and identification of their biological origins, to the identification of their modifications and breakdown patterns. This information is crucial for any restoration or conservation procedure.

The activity will be divided in technical sessions (bottom up and top down experiments), visit of museums and their restoration/conservation sections and study of specific artworks. The interactions with museums, conservators and restorers will be done via (i) the LeadART network (resulting from JPI-JHEP project 2014-2017, coordinator: C. Tokarski), and (ii) the NordART network (coordinator C. Tokarski) that links research, museums (Louvre, Matisse museum, etc.) and archaeology in the North of France. The analytical sessions will include both bottom up and top down approaches. Bottom-up proteomics is the current proteomics mainstream. Particular focus will be given to sample preparation (according to the type of sample), analytical workflow adapted to the study of very small sample amounts (on-line nanoLC nanoESI-Orbitrap MS), instrument settings, and bioinformatic tools (commercial softwares and custom-developed ones) used for protein identification, identification of common and uncommon protein modifications, identification of biological species, study of proteins from unsequenced genomes. The second part of the analytical session will focus on the top down approach (see Chem Rev 2015), using a high-resolution MS analyzer and the direct fragmentation of proteins without preliminary chemical or enzymatic hydrolysis. Particular cautions related to the sample preparation are needed and will be shown during the project (e.g. intact proteins extraction from their complex matrix). Top down experiments will be applied to the study of protein extracts from various ancient artworks using nanoLC nanoESI-Qh-FT-ICR MS including CID (Collision Induced Dissociation), ECD (Electron Capture Dissociation) and IRMPD (InfraRed MultiPhoton Dissociation) experiments. The impact of commonly used restoration tools will be studied at molecular level on model samples formulated in the lab with ancient recipes and on ancient samples restored/non restored in Partners’museums. Proteins truncations and chemical modifications will be studied.

Networking

Planned secondments:

1. Secondment period of 4 months at UCPH (co-supervision) to share and compare experience in paint binders analysis.

2. Secondment period of 3 months at the conservation section of one of the Museum in the NordART network, to optimise, together with curators and restorers, the most effective and less invasive sampling procedure.

Samples investigated in this project will be shared with UCAS, to contrast with pigment investigations on materials in China, and with UCPH.