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Int J Biol Macromol. 2018 Jan;106:1258-1269. doi: 10.1016/j.ijbiomac.2017.08.120. Epub 2017 Aug 26.

Structure, chaperone-like activity and allergenicity profile of bovine caseins upon peroxynitrite modification: New evidences underlying mastitis pathomechanisms.

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Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran.
Department of Pathology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
Immunology, Asthma, and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Institute of Biochemistry and Biophysics, Tehran University, Tehran, Iran.
Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran. Electronic address:


Mastitis, an inflammatory reaction frequently develops in response to intra-mammary bacterial infection‌‌, may induce the generation of peroxynitrite (PON)‌ which is a highly potent reactive oxygen and nitrogen species. Caseins as the intrinsically unfolded proteins seem feasible substrates to react with PON. Therefore, in the current study, structural and functional aspects of both β-casein (β-CN) and whole casein fraction (WCF) were evaluated after PON modification, using a variety of techniques. Modification of the bovine caseins with PON results in an important enhancement in the carbonyl, nitrotryptophan, nitrotyrosine and dityrosine content of these proteins‌. The results of fluorescence and far UV-CD assessments suggested significant structural alteration of caseins upon PON-modification. The chaperone-like activity of β-casein was significantly altered after PON modification. The results of scanning electron microscopy suggest that bovine caseins display unique morphological features after treatment with PON. Also, the PON-modified caseins preserved their allergenicity profile and displayed partial resistance against digestion by the pancreatic proteases. Ascorbic acid, an important antioxidant component of milk, was also capable to significantly prevent the PON-induced structural damages in bovine milk caseins. In conclusion, our results suggest that PON may have significant role in the structural and functional alteration of milk caseins. Also, the PON-induced structural damaging effects of caseins might be effectively prevented by a sufficient level of milk antioxidant components particularly by ascorbic acid.


Ascorbate; Mastitis; Peroxynitrite; Structure alteration; β-casein (β-CN)

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