How the Triton X-100 modulates the activity/stability of the Thermomyces lanuginose lipase: Insights from experimental and molecular docking approaches

The lipase and Triton X-100 mixture is common for stabilization, immobilization and application processes of these kinds of enzymes. The objective of this article was to study the structural behavior and catalytic performance of Thermomyces lanuginose lipase in the presence of Triton X-100 at 25 °C and different pHs. The structural changes were followed by circular dichroism, correlating them with the catalytic performance, which is reported as the initial lipase activity in the hydrolysis of p‑nitro phenyl butyrate at zero time and residual activity after 48 h of incubation in the absence or presence of surfactant, at the selected pHs. Computational simulations allowed to explain the correlations between the physicochemical changes and the formation of surfactant protein complex, leading to the elucidation of the main interactions that drive activity and stability of this lipase in presence of the Triton X-100 surfactant. Main results showed the Triton X-100-enzyme complex modulates the site active geometry, favoring a better substrate-enzyme adjustment, which influences the activity and stability at evaluated pHs. This study contributes to understand the effect of some additives commonly used to improve the biocatalytic performance on several applications for different industrial fields.

Controlled drug release through regulated biodegradation of poly(lactic acid) using inorganic salts

Biodegradation rate of poly(lactic acid) (PLA) has been regulated, both increase and decrease with respect to the biodegradation of pure PLA, by embedding meager amount of inorganic salts in polymer matrix. Biodegradation is performed in enzyme medium on suspension and film and the extent of biodegradation is measured through spectroscopic technique which is also verified by weight loss measurement. Media pH has been controlled using trace amount of inorganic salt which eventually control the biodegradation of PLA. High performance liquid chromatography confirms the hydrolytic degradation of PLA to its monomer/oligomer. Induced pH by metal salts show maximum degradation at alkaline range (with calcium salt) while inhibition is observed in acidic medium (with iron salt). The pH of media changes the conformation of enzyme which in turn regulate the rate of biodegradation. Thermal degradation and increment of modulus indicate improvement in thermo-mechanical properties of PLA in presence of inorganic salts. Functional stability of enzyme with metal salts corresponding to acidic and alkaline pH has been established through a model to explain the conformational changes of the active sites of enzyme at varying pH influencing the rate of hydrolysis leading to regulated biodegradation of PLA. The tuned biodegradation has been applied for the controlled release of drug from the polymer matrix (both sustained and enhanced cumulative release as compared to pure polymer). The cell proliferation and adhesion are influenced by the acidic and basic nature of polymeric material tuned by two different inorganic salts showing better adhesion and proliferation in calcium based composite and, therefore, suggest biological use of these composites in biomedical applications.