title: Amyloid fibril formation by native and modified bovine β-lactoglobulins proceeds through unfolded form of proteins: a comparative study.
abstract: The misfolding and extracellular amyloid deposition of specific proteins are associated with a large family of human pathologies, often called protein conformational diseases. Despite the many efforts expended to characterize amyloid formation in vitro, there is no deep knowledge about the environment (in which aggregation occurs) as well as mechanism of this type of protein aggregation. Recently, β-lactoglobulin (β-lg) was driven toward amyloid aggregation under specific extreme conditions. In the present study, citraconylation was employed to neutralize the charges on accessible lysine residues of β-lg and different approaches such as turbidimetry, thermodynamic analysis, extrinsic fluorimetry and theoretical studies have been successfully used to compare the different behaviors of the native and modified proteins. Kinetic analyses of native β-lg aggregation showed a gradual development of turbidity, whereas the modified β-lg displayed an increased propensity toward aggregation. Our results clearly demonstrated that the stability of modified β-lg is markedly reduced, compared to the native one. Using of TANGO and WALTZ algorithms (as well as modelling softwares) which describe aggregation tendencies of different parts of a protein structure, we suggested critical importance of some of the lysine residues in the aggregation process. The results highlighted the critical role of protein stability and elucidated the underlying role of hydrophobic/electrostatic interactions in lactoglobulin-based experimental system.
authors.affiliation: Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran.
authors.forename: Seyyed Abolghasem
authors.initials: SA
authors.lastname: Ghadami
authors.forename: Reza
authors.initials: R
authors.lastname: Khodarahmi
authors.forename: Sirous
authors.initials: S
authors.lastname: Ghobadi
authors.forename: Moosa
authors.initials: M
authors.lastname: Ghasemi
authors.forename: Saeed
authors.initials: S
authors.lastname: Pirmoradi
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D057927:Hydrophobic and Hydrophilic Interactions; D007782:Lactoglobulins / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D011489:Protein Denaturation; D055550:Protein Stability; D058767:Protein Unfolding; D013816:Thermodynamics
chemical_list: D000682:Amyloid; D007782:Lactoglobulins; D008239:Lysine