Complexation of Lysozyme with Sodium Poly(styrenesulfonate) via the Two-State and Non-Two-State Unfoldings of Lysozyme

Abstract

To provide an in-depth understanding of the complexation mechanism of protein and polyelectrolyte, a heating-cooling-reheating protocol was employed to study the unfolding and refolding behaviors of a model protein, lysozyme, in the presence of a negatively charged polyelectrolyte, sodium poly(styrenesulfonate) (PSS). It was found that, with elevated PSS concentration, a new state (state I) was first formed via a "two-state" conversion process and this state could further convert to a completely unfolded state (state II) via a "non-two-state" conversion. This non-two-state conversion process occurs without the coexistence of states I and II but involves the formation of various intermediate unfolded protein structures. Different from the pure lysozyme that exhibited refolding upon cooling from its heat-denatured state, lysozyme in state I could undergo unfolding upon heating but no refolding upon cooling, while lysozyme in state II did not undergo unfolding or refolding upon thermal treatments. In addition, the effects of ionic strength and molecular weight of polyelectrolyte on the unfolding and refolding behaviors of lysozyme were also investigated. The present work provides a better understanding of the principles governing protein-polyelectrolyte interactions and may have implications for the fabrication of biocolloids and biofilms.

Binding of Lysozyme to Spherical Poly(styrenesulfonate) Gels

“…Nevertheless, if the interactions between PSS and lysozyme responsible for the high density of the complexes are of hydrophobic nature they can be expected to have some effect on the conformation of the protein. In fact, Wu et al [40] recently showed that nearly charge stoichiometric complexes of lysozyme and linear PSS contain a large fraction of lysozyme in a state different from the native form. In a mixture with a PSS/lysozyme-charge ratio of 1.5 at 20 °C, where the non-native state completely dominated, the contents of α -helix and β -sheet was reported to be 18% and 30%, as compared to 36% and 14%, respectively, in the native state.…”

“…In the present paper we investigate this further by studying the binding of lysozyme to sodium poly(styrenesulfonate) (PSS) microgel spheres by means of micropipette-assisted microscopy. PSS is known to interact electrostatically and hydrophobically with lysozyme [39,40,41] and with cationic surfactant micelles [42,43,44,45], in contrast to PA which is expected to display mainly electrostatic interactions. One motive behind the study is thus to investigate how the hydrophobic backbone of PSS affects the binding and aggregation of lysozyme in gels.…”

Development and evaluation of inhalable composite niclosamide-lysozyme particles: A broad-spectrum, patient-adaptable treatment for coronavirus infections and sequalae

“…This may explain why a decrease in antiviral activity was noted with NIC solubilized in DMSO compared to NIC particles. Interactions between NIC and hLYS in the microenvironment may serve as a mechanism to disrupt this self-association and ensure availability of the electronegative functional groups, as lysozyme has been previously demonstrated to complex with negatively charged molecules [73] and a hydrophobic drug [74]. Given the physicochemical properties of NIC, both chargedbased and hydrophobic interactions with hLYS may be important.…”

Thermal resilience of ensilicated lysozyme via calorimetric and in vivo analysis

“…At this specic temperature, the vibrational energy will disrupt the native conformation causing the protein to denature, thereby losing its tertiary structure. [28][29][30] Use of this approach allows assessment of ensilicated protein in powder and native/released protein in solution, indicating whether ensilicated protein has the mobility to unfold under heating/ freezing within its silica shell. Furthermore, varying the silica ratios used for ensilication would indicate the optimised silica to protein ratio required to render a protein thermally stabilised while allowing for the easiest possible release of the protein from the silica shell.…”

“…2.1.4 Detection of 29 Si aer release. The release mechanism is a sequence of several steps that allow the ensilicated material to be released.…”