Reyes-Blas, Myrna

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    Comparative protein analysis of two human isoforms Centrin 1 and Centrin 2
    (2008) Reyes-Blas, Myrna; Pastrana-Ríos, Belinda; College of Arts and Sciences - Sciences; Vera, Marisol; López, Gustavo; Department of Chemistry; Acevedo, Aldo
    Centrin is a calcium binding protein belonging to EF-hand superfamily that is found only in eukaryotic cells from yeast to humans. Three isoforms have been identified in humans two of which are presented in this work: human centrin 1 (Hcen1) and human centrin 2 (Hcen2). Both are comprised of 172 amino acids having between them more than 80 % sequence identity. Hcen1 are localized in the central lumen of the basal bodies of the sperm and Hcen2 are mainly within centrioles. In order to know more about the structure, dynamics and relative stability we, have performed Hcen1 and Hcen2 bacterial expression, isolation, and purification; for their biophysical characterization using FT-IR spectroscopy and two dimensional correlation spectroscopy analysis. The order of events throughout the thermal perturbation was established from 1700 – 1530 cm-1 spectral region study. The thermal stability for Hcen1 is described as the follows: α-helix < β-sheets < glutamate < βturns, while for Hcen2 the thermal stability is the following: arginine < 310-helix < aspartate/glutamate < random coil < α-helix < aggregation < loops. A higher thermal stability was observed for Hcen1 than for Hcen2 and a pretransition at 1.7 – 4.8 ˚C and the onset of the transition temperature was also observed for Hcen1 at 80.5 – 84 ˚C. Unlike Hcen1, Hcen2 was observed to aggregate at the temperature range of 43 – 58 ˚C. Therefore, we were able to establish differences in stability, conformation and dynamics between these isoforms.
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    Single-step processing of Cu and Ag nanocrystals and nanocomposites for antimicrobial applications
    (2021-12-09) Reyes-Blas, Myrna; Román-Velázquez, Félix R.; College of Arts and Sciences - Sciences; Meléndez, Enrique; Pastrana-Ríos, Belinda; López-Moreno, Martha L.; Department of Chemistry; Santos-Flores, Carlos J.
    Emerging and re-emerging pathogens pose a worldwide public health risk since they can cause severe infectious diseases, which are difficult to treat due to the ineffective action of traditional treatments. Furthermore, medical treatments produce economic burdens to patients and health insurance. The development of nano-scale materials with antimicrobial properties could help avoid pathogen contamination and its dissemination. The unique physicochemical, optical, and biological properties that silver, copper and composites exhibit at nanoscale size, such as their capacity to inhibit microbial growth, make them suitable materials for medicine, therapeutics, medical devices, and food packaging applications. However, the reported procedures to synthesize metallic nanoparticles require tedious steps and toxic reagents. In this work, two approaches were performed to synthesize metallic nanoparticles using microwave-assisted synthesis in a single-step. In the first approach, silver nanoparticles (Ag NPs) were synthesized in an aqueous environment and functionalized with the peptide glutathione (GSH) to facilitate the passage of the Ag NPs through the cell membrane. In the second approach, a modified polyol method was established to synthesize Ag NPs and copper nanoparticles (Cu NPs), allowing the co-reduction and formation of silver-copper nanoparticles (AgCu NPs). The synthesized nanoparticles were characterized using High-Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive X-Ray (EDX), X-Ray Diffraction (XRD), X-Ray Photoelectron (XPS), Fourier Transform Infrared (FT-IR), and Ultraviolet-Visible (UV-Vis) spectroscopic techniques. The Ag-GSH NP antimicrobial properties were evaluated against Listeria monocytogenes and Escherichia coli O157: H7 strains. Those pathogens were isolated from produce outbreaks and tested on baby spinach leaves. Also, Ag NPs, Cu NPs and AgCu NPs antimicrobial properties were evaluated against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Candida albicans. By following our approach, AgCu NPs were successfully synthetized and showed enhanced antimicrobial properties against Gram-positive and Gram-negative bacteria at lower concentration than single metal NP. This shows their potential application as an alternative against antibiotic resistance.