title: α-Casein inhibition mechanism in concanavalin A aggregation process.
abstract: The inhibition of the aggregation in protein solutions is currently a subject of great interest in many research fields, from the study of protein-misfolding related diseases to pharmaceutics, biotechnology, and food science. α(s1)-Casein, one of the four types of caseins, which are the largest protein component of bovine milk, has been found to hinder the aggregation process of several proteins, including the amyloid β-peptide, involved in Alzheimer's disease. To shed light into the mechanisms by which casein exerts this chaperon-like protective action, we studied its effect on the different steps of the aggregation process of concanavalin A, by means of both static and dynamic light scattering, thioflavin T and ANS fluorescence, circular dichroism, and atomic force microscopy. Our results show that casein has a poor effect on the first step of the process leading to the formation of amyloid-like structures. On the contrary, it has a marked effect on the second step of the process, ascribable to clusters condensation and compaction, up to the formation of very large aggregates. Such an effect requires a molar ratio of casein larger than that necessary to inhibit the fibrillogenesis of the amyloid β-peptide, thus, suggesting a different mechanism of interaction of casein, depending on both conformational properties and relative size of the aggregating molecules.
authors.affiliation: Institute of Biophysics, The National Research Council, Via Ugo La Malfa 153, 90146 Palermo, Italy. rita.carrotta@pa.ibf.cnr.it
authors.forename: Rita
authors.initials: R
authors.lastname: Carrotta
authors.forename: Silvia
authors.initials: S
authors.lastname: Vilasi
authors.forename: Fabio
authors.initials: F
authors.lastname: Librizzi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Martorana
authors.forename: Donatella
authors.initials: D
authors.lastname: Bulone
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: San Biagio
mesh_terms: D002364:Caseins / Q000494:pharmacology*; D003208:Concanavalin A / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D055503:Protein Multimerization / Q000187:drug effects*; D017433:Protein Structure, Secondary
chemical_list: D002364:Caseins; D003208:Concanavalin A