Exploring Enzymatic Conformational Dynamics at Surfaces through µ-FTIR Spectromicroscopy.

Immobilization of proteins onto solid supports has critical industrial, technological, and medical applications, and is a daily task in chemical research. Significant conformational rearrangements often occur due to enzyme-surface interactions, and it is of broad interest to develop methods to probe and better understand these molecular-level changes that contribute to the enzyme's catalytic activity and stability. While circular dichroism is a common method for solution-phase conformational study, the application to surface-supported proteins is not trivial and spatial mapping is not viable. On the other hand, a nonlinear laser spectroscopy technique used to analyze surfaces and interfaces is not often found in most laboratories, therefore requiring an alternative and reliable method. Here, we employed high-dimensional data spectromicroscopy analysis in the infrared region (µ-FTIR) to investigate the enzyme's conformational change when adsorbed onto solid matrices, across a ca. 20 mm2 area. Alcohol dehydrogenase (ADH) enzyme was adopted as a model enzyme to interact with CaF2, Au, and Au-thiol model substrates, strategically chosen for mapping the enzyme dynamics on solid surfaces with different polarity/hydrophobicity properties and extendable to other materials. Two-dimensional chemical maps indicate that the enzyme adsorbs with different patterns in which secondary structures dynamically adjust to optimize interprotein and enzyme-surface interactions. The results suggest an experimental approach to identify and map enzyme conformational dynamics onto different solid surfaces across space and provide insights into immobilized protein structure investigations for areas such as biosensing and bioenergy.

Synthesis and antiplasmodial assessment of nitazoxanide and analogs as new antimalarial candidates.

During the last years, the progression to control malaria disease seems to be slowed and WHO (World Health Organization) reported a modeling analysis with the prediction of the increase in malaria morbidity and mortality in sub-Saharan Africa during the COVID-19 pandemic. A rapid way to the discovery of new drugs could be carried out by performing investigations to identify drugs based on repurposing of "old" drugs. The 5-nitrothiazole drug, Nitazoxanide was shown to be active against intestinal protozoa, human helminths, anaerobic bacteria, viruses, etc. In this work, Nitazoxanide and analogs were prepared using two methodologies and evaluated against P. falciparum 3D7. A bithiazole analog, showed attractive inhibitory activity with an EC50 value of 5.9 µM, low propensity to show toxic effect against HepG2 cells at 25 µM, and no cross-resistance with standard antimalarials.