Caroline Tokarski

Deciphering milk processing used in Ist century nursing bottle using top down proteomics

Fabrice Bray§, Mathieu Dupre£, Sandra Jaeggi#, Stéphanie Devassine§, Nicolas Garnier±, Christian Rolando§, Julia Chamot-Rooke£, Caroline Tokarski§,*

§ Miniaturization for Synthesis, Analysis & Proteomics (MSAP), CNRS USR 3290, University of Lille, Faculty of Sciences and Technologies, 59655 Villeneuve d’Ascq, France; £ Institut Pasteur, Mass Spectrometry for Biology Unit CNRS USR 2000, 28, rue du Dr. Roux, 75015 Paris, France; # University of Fribourg, Department of Archaeology, av. du Criblet 13, 1700 Fribourg, Switzerland; ± SARL Laboratoire Nicolas Garnier, 63270 Vic le Comte, France; *Corresponding Author E-Mail: Caroline.Tokarski@univ-lille1.fr

The protein content of archaeological objects informs on societal events from past civilization. We report here a new analytical methodology based on top down proteomics for the identification of proteins and their chemical modifications from non-visible remains in archaeological ceramics.

One of the main focus of the study is lactosylation, a non-enzymatic glycation that signs the heating treatment of milk. Lactulosyllysine Amadori product, resulting from a rearrangement of the Schiff base formed by ε -amino group of lysine and lactose, was studied in various model samples such as heated milk versus non heated milk from impregnated ceramics or milk skin.

Applied to the study of Ist century nursing bottles (Zurzach, Argovie, Switzerland), milk proteins such as caseins and lactoglobulins from bovine origin were accuratey identified including their phosphorylation. Remarkable sequence coverages up to 100% were obtained (not achieved using a bottom up approach for same samples); e.g. alphaS1 casein was identified by two peptides covering its full sequence (16-116 and 101-214; 1-15 is the signal peptide). Sequential C-terminus-side degradations of proteins were also observed. Concerns related to the processing of milk are argued. Overall, the full analytical workflow based on filter aided sample preparation and high resolution mass spectrometry / EThcD experiments (electron transfer / higher energy collision dissociation) will be detailed during the conference.

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