Aflatoxin M-1 binding to bovine alpha- and kappa-caseins demonstrated by surface plasmon resonance

A preliminary investigation of the potential binding interaction of isolated whey proteins and casein proteins with aflatoxin M-1 (AFM(1)) 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 AFM(1) differentially binds to alpha-casein and kappa-casein; it has negligible interaction with beta-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 AFM(1) in milk and milk products that have only indirectly proposed its affinity for casein. (C) 2021 Elsevier Ltd. All rights reserved.