title: Sodium dodecyl sulphate (SDS) induced changes in propensity and kinetics of α-lactalbumin fibrillation.
abstract: Understanding surfactants induced changes on protein folding, aggregation, and fibrillation has a lot of implications in their laboratory and industrial applications. The effect of an anionic surfactant, sodium dodecyl sulphate (SDS), on fibrillation of an acidic protein α-lactalbumin (α-LA) at neutral pH condition was investigated. SDS at lower concentrations increased the lag time by nearly two-fold whereas the fibril elongation rate was not significantly altered. At the concentrations above 0.2mM, SDS lengthened the lag time by many-fold (∼60), but fibril elongation was accelerated by 3-6 fold. At the concentrations above 2mM, SDS inhibited α-LA fibrillation and led it to the formation of amorphous aggregates. These results were compared with the effect of SDS on the fibrillation of lysozyme, a basic protein. Though fibril inhibition was observed on both the proteins at the micellar concentrations of SDS, there were differences in the effect on lag time and elongation rate at the lower concentrations of SDS. This suggests that the inhibition of protein fibrillation by SDS-micelles might be a common mechanism irrespective of the surface charges on protein.
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: E Kiran
authors.initials: EK
authors.lastname: Kumar
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: Shamsul
authors.initials: S
authors.lastname: Qumar
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India. Electronic address: nppsl@uohyd.ernet.in.
authors.forename: N Prakash
authors.initials: NP
authors.lastname: Prabhu
mesh_terms: D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007768:Lactalbumin / Q000737:chemistry*; D066329:Protein Aggregates / Q000187:drug effects; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D058767:Protein Unfolding; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry* / Q000494:pharmacology; D013501:Surface-Active Agents / Q000737:chemistry / Q000494:pharmacology
chemical_list: D066329:Protein Aggregates; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D007768:Lactalbumin
keywords: Elongation; Fibril; Lag time; SDS; Surfactant; α-Lactalbumin