The Binding of Sodium Dodecyl Sulfate to Lysozyme in Aqueous Solutions

Abstract

The binding mode of sodium dodecyl sulfate to lysozyme and the accompanying structural change of lysozyme by binding have been investigated by means of the binding isotherm, the precipitation curve, and the CD spectra in pure water, NaCl, and borate buffer solutions. The precipitation phenomena could be explained in terms of the neutralization of the net charge of lysozyme due to dodecyl sulfate-ion binding. The analysis of the binding isotherms by the use of the BET equation gave the site number of the first layer corresponding to the positively charged residues at the pH studied. The conformational change from the β-structure to the α-helix has been observed in the second-layer binding. The environmental change of the side-chain residues has also been observed.

A small-angle X-ray scattering study of the structure of lysozyme–sodium dodecyl sulfate complexes

“…[1]. Many early polymer-surfactant studies involved proteins [2], and the proteinsurfactant interactions have since been studied extensively [3][4][5][6][7][8][9][10][11][12][13]. These interactions are important in several biochemical separation methods, food emulsions, pharmaceuticals, personal care products, etc.…”

“…Although the fluorescence probe [9,10], phase behavior [21,22], binding isotherm [5,12,23] and clouding studies [24,25] indicate similar qualitative behavior of BSA-SDS and lysozyme-SDS complexes, there are several subtle differences such as the difference in the number of micellar clusters per protein molecule, the aggregation number of micelles, the sensitivity of clouding temperature to protein/surfactant weight ratio, etc. BSA-SDS is often used as archetype system in the study of protein-surfactant interactions.…”

Aggregation in a Protein−Surfactant System. The Interplay between Hydrophobic and Electrostatic Interactions

“…[3][4][5][6] The concentrations have been such that the phase transitions with increasing surfactantto-protein ratio can be expressed as an initial precipitation of a stoichiometric complex salt, followed by a resolubilization to a charged complex. 7 It is the latter soluble complex that has received major attention in the past. The present work, with lysozyme and sodium octyl sulfate, SOS, features a different resolubilization route, via a gel phase.…”

Surfactant–Amino Acid and Surfactant–Surfactant Interactions in Aqueous Medium: a Review

“…Protein-surfactant interactions have been extensively studied in aqueous solutions [20][21][22][23][24]. Both oppositely [25][26][27] and similarly [28,29] charged protein-surfactant and protein-nonionic surfactant systems are being studied [30]. The understanding of the interactions is complicated because proteins are complex macromolecules with a distinctive primary structure articulated in terms of their amino acid sequences.…”