Proteomics and Cultural Heritage

Proteins represent an important constituent in many art and archaeological objects. Notable proteinaceous materials, such as animal glue, egg (both yolk and albumen) and milk have long been used in artwork as painting binders, as adhesives for gildings, or they were included in mortars and paint grounds. The identification of protein-based material is an important information to understand the manufacturing process; it provides insights in the technique used by an artist, essential information for art historians. Moreover, it may also support the choice of the most appropriate conservation or restoration procedures. Proteomics is typically considered to be associated with the study of living organisms. However, its inherently multidisciplinary nature has recently led to its application to oddly assorted areas ranging from forensics, food analysis, and clinical medicine and even for studying the origins of life. In recent years, proteomics procedures have become increasingly popular for the characterization of proteinaceous materials in ancient samples of several cultural heritage objects. Proteomics for cultural heritage is still in its infancy, with the first paper dating back to the early 2000. In particular, protocols routinely applied for typical modern samples still need to be fully adapted to take into account the low amount of proteinaceous material, the heterogeneity and the unusual physical state of the samples, as well as the high levels of damage found in ancient samples. Modern mass spectrometry instrumentations are perfectly adequate to afford the minimal quantities of ancient samples. A micro-invasive protocol, in fact, proved to be successful when applied to fragments of paintings from the collapsed vault of the Basilica di S. Francesco in Assisi, and samples collected from the Camposanto Monumentale in Pisa. Generally, by the use of these methods, we can easily identify complex protein mixtures in very complex and heterogeneous matrix. Nevertheless, samples coming from artwork have an intrinsic contamination problem that originates from environmental exposure. In addition, the physical state of the samples, enormously different from the natural environment of proteins, and the degradation processes undergone during aging provide unusual problems that require to be counteracted. Therefore, all the steps of the proteomic procedure need to be thoughtfully adapted, from the optimization of specific protocols for sample preparation to the development of data analysis tools that can cope with ancient or damaged samples. In this perspective, my PhD project was devoted to this challenge as well as to the specific application of the developed strategies to diverse samples from works of art

Proteomic strategies for cultural heritage: From bones to paintings

In recent years, proteomics procedures have become increasingly popular for the characterization of proteinaceous materials in ancient samples of several cultural heritage objects. The knowledge of the materials used in a work of art is crucial, not only to give an insight in the historical context of objects and artists, but also to analyse degradation processes taking place in aged objects and to develop appropriate conservation and/or restoration treatments. However, protocols routinely applied for typical modern samples still need to be fully adapted to take into account the low amount of proteinaceous material, the heterogeneity and the unusual physical state of the samples, as well as the high levels of damage found in ancient samples. This paper deals with some examples of the adaptation of classical proteomic strategies in the analysis of ancient samples to meet the different aims in the cultural heritage field

Stinging Nettles as Potential Food Additive: Effect of Drying Processes on Quality Characteristics of Leaf Powders

Abstract: Stinging nettle (Urtica dioica L.) is a ubiquitous, multi-utility, and under-utilized crop with potential health benefits owing to its nutritional and bioactive components. The objective of the work is to produce powders by drying wild stinging nettle leaves as a storable, low-cost functional additive to be used in bakery and ready-to-cook products. Convective drying (CD) and freeze-drying (FD) were applied on unblanched (U) or blanched (B) leaves, which were then milled to nettle powders (NPs). The obtained NPs were evaluated for selected physicochemical (moisture, color), techno- functional (flow indices, hygroscopicity), and phytochemical (pigments, phenols) characteristics as well as mineral contents. Blanching improved mass transfer and reduced the oxidative degradation of pigments during drying, but it caused a loss of total phenols content, antioxidant activity, and potassium content. As for the drying method, CD resulted in better flow properties (i.e., Carr Index and Hausner Ratio), while FD retained better the color, pigments, magnesium content, phenolic, and antioxidant parameters. Overall, the evaluated processing methods resulted in different technological properties that can allow for better evaluation of NPs as a food additive or ingredient. Among the NPs, blanched and freeze-dried powders despite showing inferior technological properties can be recommended as more suitable ingredients targeted f or food enrichment owing to better retention of bio-active components

Identification of proteinaceous binders in paintings: A targeted proteomic approach for cultural heritage

Abstract Identification of proteins in paintings and polychrome objects is a challenge, which requires the development of tailored analytical approaches. In the present study, a targeted proteomics approach was developed for discriminating among the three most common proteinaceous materials used as paint binders, i.e. milk, egg, and animal glue. In this study a specific database of peptides was created based on tandem MS analyses of tryptic digests of several paint samples collected from a variety of art objects of different ages and conservation conditions. Specific peptide markers of each protein were then selected and monitored by LC-MSMS in Multiple Reaction Monitoring (MRM) ion mode, together with their specific precursor ion-product ion transitions, as defined by their unique amino acid sequence. The developed method enabled a sensitive and reliable detection of the target peptides in a selection of case studies, leading to the unambiguous identification of the proteins used as paint binders. The method showed greatly increased sensitivity compared to currently available strategies

Proteomic Characterization of Collagen-Based Animal Glues for Restoration

Animal glues are widely used in restoration as adhesives, binders, and consolidants for organic and inorganic materials. Their variable performances are intrinsically linked to the adhesive properties of collagen, which determine the chemical, physical, and mechanical properties of the glue. We have molecularly characterized the protein components of a range of homemade and commercial glues using mass spectrometry techniques. A shotgun proteomic analysis provided animal origin, even when blended, and allowed us to distinguish between hide and bone glue on the basis of the presence of collagen type III, which is abundant in connective skin/leather tissues and poorly synthetized in bones. Furthermore, chemical modifications, a consequence of the preparation protocols from the original animal tissue, were thoroughly evaluated. Deamidation, methionine oxidation, and backbone cleavage have been analyzed as major collagen modifications, demonstrating their variability among different glues and showing that, on average, bone glues are less deamidated than hide glues, but more fragmented, and mixed-collagen glues are overall less deamidated than pure glues. We believe that these data may be of general analytical interest in the characterization of collagen-based materials and may help restorers in the selection of the most appropriate materials to be used in conservation treatments

Notes on the distribution of Castnia invaria penelope Schaufuss, 1870 (Lepidoptera, Castniidae)

The finding of Castnia invaria penelope Schaufuss, 1870 in Ecuador (Rio Napo) is highlighted, thus extendingthe body of knowledge on the distribution of the ssp. Additional information on the genus and the congenericspecies is also provided

OSSERVAZIONI SUL GENERE ALCIDES HÜBNER [1822] E DESCRIZIONE DI DUE NUOVE SPECIE DELL’INDONESIA (LEPIDOPTERA, URANIIDAE)

Vengono descritte e raffigurate due nuove specie del genere Alcides Hübner, [1822] dell’Indonesia, Irian Jaya: Alcides privitera n. sp. (Sorong) ed Alcides leone n. sp. (Timika e Sorong), fornendo, altresì, alcuni dati sul genere di appartenenza. Le femmine e gli stadi preimaginali dei nuovi taxa sono attualmente ignoti

Vinciguerra_Vinciguerra

ABSTRACT The finding of Castnia invaria penelope Schaufuss, 1870 in Ecuador (Rio Napo) is highlighted, thus extending the body of knowledge on the distribution of the ssp. Additional information on the genus and the congeneric species is also provided

Identification and Characterisation of a Pectinolytic Enzyme from Paenibacillus xylanolyticus

Pectinolytic enzymes have an important role in the processing of lignocellulosic materials because of their ability to improve the access of cellulases to their substrate by removing pectins. The strain Paenibacillus xylanilyticus 2-6L3 was isolated from mature compost obtained from agro-industrial wastes, and the enzyme pectate lyase from P. xylanilyticus 2-6L3, named Paenxyl Pel, was partially purified and subjected to structural and functional characterisation. The enzyme exhibited an optimum temperature between 60 and 70 °C and optimal pH value of 9.0 for its pectinase activity on pectin from citrus fruit. Paenxyl Pel showed a thermoresistance and pH resistance higher than those of other pectate lyases so far described, with half-lives of 48 and 24 h at 60 and 70 °C, respectively, a retention of around 80% of activity after 96 h at 40 and 50 °C, and a half-life of about 15 days at pH 8.0. Paenxyl Pel followed Michaelis-Menten kinetics toward pectin from citrus fruit, pectin from sugar beet pulp, high-ester pectin extracted from citrus peel (> 50% esterified), and polygalacturonic acid (PLA). The ability to act on both PLA and highly methylated pectins, together with a double peak in the graph of optimum pH at pH 5 and 9, suggest that pectate lyase from P. xylanoliticus shows an unusual activity, combining traits of pectate lyase and pectin lyase. This is the first manuscript on the pectinolytic activity of P. xylanilyticus