Журнал хроматографии и методов разделения
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Structural Characterization of Transglutaminase-Catalyzed Casein Cross- Linking

Sergio Lilla, Gianfranco Mamone, Maria Adalgisa Nicolai, Lina Chianese, Gianluca Picariello, Simonetta Caira and Francesco Addeo

Microbial transglutaminase is used in the food industry to improve texture by catalyzing protein cross-linking. Casein is a well-known transglutaminase substrate, but the complete role of glutamine (Q) and lysine (K) residues in its cross-linking is not fully understood. In this study, we describe the characterization of microbial Transglutaminase -modified casein using a combination of immunological and proteomic techniques. Using 5-(biotinamido)pentylamine as an acyl acceptor probe, three Q residues of β-casein and one of αs1-casein were found to participate as acyl donors. However, no Q-residues were involved in network formation with κ-casein or αs2-casein. Q and K residues in the ε-(γ-glutamyl)lysine-isopeptide bonds β-casein were identified by nanoelectrospray tandem mass spectrometry of the proteolytic digests. This work reports our progress toward a better understanding of the function and mechanism of action of microbial transglutaminase-mediated proteins. The results suggest a possible role for transglutaminase in the formation of casein micelles.