Aflatoxin M1 binding to bovine α- and κ-caseins demonstrated by surface plasmon resonance

A preliminary investigation of the potential binding interaction of isolated whey proteins and casein proteins with aflatoxin M1 (AFM1) using a surface plasmon resonance optical biosensor is described. The experimental conditions were restricted to facilitate a qualitative analysis that, for the first time, has demonstrated that AFM1 differentially binds to α-casein and κ-casein; it has negligible interaction with β-casein and the individual whey proteins. These observations with individual casein proteins can be extrapolated to infer that such differential binding occurs in intact milk, and explains the many previous reports of the heterogeneous distribution of AFM1 in milk and milk products that have only indirectly proposed its affinity for casein.