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"Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Access "; International audience

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The primary structures of ovine alpha(s1)-casein variants A, C and D (formerly called Welsh variant) were determined. Separation of variants from whole casein was achieved using a fast and reliable reversed-phase HPLC method. Extended structural characterization of the purified proteins using electrospray mass spectrometry, automated Edman degradation and peptide mapping by means of HPLC-fast atom bombardment-mass spectrometry demonstrated that the mature protein was a mixture of two molecular species that differed in the deletion of residues 141-148 and were therefore 199 and 191. residues long respectively. The 199 residue peptide chain, which accounted for similar to 80% of the entire translated alpha(s1)-casein, was as long as its caprine and bovine counterparts, and had a 98 and 89% degree of identity with those two proteins respectively. Nine serine residues (positions 12, 44, 46, 64 to 68 and 75) were fully phosphorylated in alpha(s1)-casein A, whereas Ser(115) and Ser(41) were phosphorylated by similar to 50 and similar to 20% respectively. The differences between the three genetic variants A, C and D were simple silent substitutions, which however involved the degree to which the protein was phosphorylated. Variant C differed from variant A in the substitution Ser(13) --> Pro(13) which determined the loss of the phosphate group on site 12 of the protein chain, SerP(12) --> Ser(12). A further substitution, SerP(68) --> Asn(68) caused the disappearance of both phosphate groups in the phosphorylated residues Ser(64) and Ser(66) in variant D; in this last casein variant there was no evidence of phosphorylation at Ser(41).

International audience

International audience

International audience

International audience

International audience

The revolution of 'omic' sciences has introduced integrated high-throughput approaches to address the understanding of the biochemical systems and of their dynamic evolution. In the field of food research, 'omics' are depicting a comprehensive view which largely overcomes the merely descriptive approaches of the early proteomic and metabolomic era. Thus, the recently born 'foodomics' is to be intended as a global perspective of knowledge about foods, which covers the assessment of their composition, the effects of (bio)technological processes for their production, their modifications over time and the impact that food consumption has on human health. Food proteomics and metabolomics, along with their derived 'omic' branches such as peptidomics, lipidomics and glycomics, are still evolving technologies capable of tackling the nature and the transformations of foods. In the development of the advanced 'omic' platforms, because of their potential to profile complex mixtures of biomolecules, mass spectrometry techniques have assumed an unquestionable role. Because proteins are central molecules in all biological systems, proteomic platforms are pivotal among the 'foodomic' tools, as the proteomes and related peptidomes provide biomolecular subsets mostly informative about the history of a food product. Similarly, food interactomics and metabonomics aim to study the dynamics that occur in foodstuff. The ultimate aim of foodomics is the production of high-quality and safe food products for improving human health and well-being. In this review we critically present the recent research outcomes in the field of food sciences that have been achieved through the contribution of the 'omic' methodologies relying on mass spectrometry.

A novel electrophoretic alpha-lactalbumin (alpha-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0(.)5% compared with the 97(.)1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two alpha-la A and B variants were measured as 14235(.)1 +/- 0(.)8 and 14236(.)1 +/- 0(.)9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn(45)(B)-->Asp(45)(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45-X-Ser(46) it may be deduced that the protein glycosylation level of the alpha-la A would decrease.