Effect of nonenzymatic deamidation on the structure stability of Camelus dromedarius α-lactalbumin.

Affiliation

Université de Lorraine, INRA, Unité de Recherche Animal et Fonctionnalités des Produits Animaux (UR AFPA), USC 340, Nancy F-54000, France. Electronic address: [Email]

Abstract

Camelid α-lactalbumin is the only known protein that can undergo nonenzymatic deamidation on two Asn residues. This leads to the generation of a mixture of unusual isoAsp and d-Asp residues that may impact health. The effect of deamidation on camel α-lactalbumin instability was investigated. Circular dichroism showed that the altered protein acquired secondary structure resulting in an increase in α-helix content. In good agreement, the 3D structure of camel α-lactalbumin determined by X-ray crystallography, displayed a short additional α-helix probably induced by deamidation, compared to the human and bovine counterparts. This α-helix was located in the C-terminal region and included residues 101-106. Differential scanning calorimetry together with the susceptibility to thermolysin showed that the deamidation process reinforced the structural stability of the α-lactalbumin at high temperature and its resistance toward proteolysis.

Keywords

Camel α-lactalbumin,Circular dichroism,Differential scanning calorimetry,Nonenzymatic deamidation,Thermolysin,X-ray crystallography,

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