Publications by authors named "Tiffany Suwatthee"

2 Publications

  • Page 1 of 1

Beyond electrostatics: Antimicrobial peptide selectivity and the influence of cholesterol-mediated fluidity and lipid chain length on protegrin-1 activity.

Biochim Biophys Acta Biomembr 2019 10 8;1861(10):182977. Epub 2019 May 8.

Department of Chemistry, Institute for Biophysical Dynamics and James Frank Institute, The University of Chicago, Chicago, IL 60637, United States. Electronic address:

Antimicrobial peptides (AMPs) are a promising class of innate host defense molecules for next-generation antibiotics, as they uniquely target and permeabilize membranes of pathogens. This selectivity has been explained by the electrostatic attraction between these predominantly cationic peptides and the bacterial membrane, which is heavily populated with anionic lipids. However, AMP-resistant bacteria have non-electrostatic countermeasures that modulate membrane rigidity and thickness. We explore how variations in physical properties affect the membrane affinity and disruption process of protegrin-1 (PG-1) in phosphatidylcholine (PC) membranes with altered lipid packing densities and thicknesses. From isothermal titration calorimetry and atomic force microscopy, our results showed that PG-1 could no longer insert into membranes of increasing cholesterol amounts nor into monounsaturated PC membranes of increasing thicknesses with similar fluidities. Prevention of PG-1's incorporation consequently made the membranes more resistant to peptide-induced structural transformations like pore formation. Our study provides evidence that AMP affinity and activity are strongly correlated with the fluidity and thickness of the membrane. A basic understanding of how physical mechanisms can regulate cell selectivity and resistance towards AMPs will aid in the development of new antimicrobial agents.
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http://dx.doi.org/10.1016/j.bbamem.2019.04.011DOI Listing
October 2019

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay.

Rev Sci Instrum 2017 Mar;88(3):033112

James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl at pH 7.5. Data analysis with XeRay reveals that each 1 nm of interfacial area contains 2.38 ± 0.06 Ca ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr at 68 Å per ion, consistent with the result published for the same dataset.
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http://dx.doi.org/10.1063/1.4978654DOI Listing
March 2017