Chemistry Commons^™

Aircraft-Engine Particulate Matter Emissions From Conventional And Sustainable Aviation Fuel Combustion: Comparison Of Measurement Techniques For Mass, Number, And Size, Joel C. Corbin, Tobias Schripp, Bruce E. Anderson, Greg J. Smallwood, Patrick Leclercq, Ewan C. Crosbie, Steven Achterberg, Philip D. Whitefield, Richard C. Miake-Lye, Zhenhong Yu, Andrew Freedman, Max B. Trueblood, David Satterfield, Wenyan Liu

Chemistry Faculty Research & Creative Works

Sustainable aviation fuels (SAFs) have different compositions compared to conventional petroleum jet fuels, particularly in terms of fuel sulfur and hydrocarbon content. These differences may change the amount and physicochemical properties of volatile and non-volatile particulate matter (nvPM) emitted by aircraft engines. In this study, we evaluate whether comparable nvPM measurement techniques respond similarly to nvPM produced by three blends of SAFs compared to three conventional fuels. Multiple SAF blends and conventional (Jet A-1) jet fuels were combusted in a V2527-A5 engine, while an additional conventional fuel (JP-8) was combusted in a CFM56-2C1 engine. We evaluated nvPM mass concentration measured …

Relating Detonation Parameters To The Detonation Synthesis Of Silicon Carbide, Martin Langenderfer, Eric W. Bohannan, Jeremy Lee Watts, William Fahrenholtz, Catherine E. Johnson

Chemistry Faculty Research & Creative Works

Detonation synthesis of silicon carbide (SiC) nanoparticles from carbon liberated by negatively oxygen balanced explosives was evaluated in a 23 factorial design to determine the effects of three categorical experimental factors: (1) cyclotrimethylene-trinitramine (RDX)/2,4,6-trinitrotoluene (TNT) ratio, (2) silicon (Si) additive concentration, and (3) Si particle size. These factors were evaluated at low and high levels as they relate to the detonation performance of the explosive and the solid Si-containing phases produced. Detonation velocity and Chapman-Jouguet (C-J) detonation pressure, which were measured using rate stick plate dent tests, were evaluated. Solid detonation product mass, silicon carbide product concentration, and residual silicon …

Defining The Collapse Point In Colloidal Unimolecular Polymer (Cup) Formation, Ashish Zore, Peng Geng, Yuwei Zhang, Michael R. Van De Mark

Chemistry Faculty Research & Creative Works

Colloidal unimolecular polymer (CUP) particles were made using polymers with different ratios of hydrophobic and hydrophilic monomers via a self-organization process known as water reduction. The water-reduction process and the collapse of the polymer chain to form a CUP were tracked using viscosity measurements as a function of composition. A vibration viscometer, which allowed for viscosity measurement as the water was being added during the water-reduction process, was utilized. The protocol was optimized and tested for factors such as temperature control, loss of material, measurement stability while stirring, and changes in the solution volume with the addition of water. The …

Defining The Collapse Point In Colloidal Unimolecular Polymer (Cup) Formation, Ashish Zore, Peng Geng, Yuwei Zhang, Michael R. Van De Mark

Chemistry Faculty Research & Creative Works

Colloidal unimolecular polymer (CUP) particles were made using polymers with different ratios of hydrophobic and hydrophilic monomers via a self-organization process known as water reduction. The water-reduction process and the collapse of the polymer chain to form a CUP were tracked using viscosity measurements as a function of composition. A vibration viscometer, which allowed for viscosity measurement as the water was being added during the water-reduction process, was utilized. The protocol was optimized and tested for factors such as temperature control, loss of material, measurement stability while stirring, and changes in the solution volume with the addition of water. The …

Establishing Pteridine Metabolism In A Progressive Isogenic Breast Cancer Cell Model – Part Ii, Lindsey Rasmussen, Zachary Foulks, Jiandong Wu, Casey Burton, Honglan Shi

Chemistry Faculty Research & Creative Works

Introduction: Determining the biological significance of pteridines in cancer development and progression remains an important step in understanding the altered levels of urinary pteridines seen in certain cancers. Our companion study revealed that several folate-derived pteridines and lumazines correlated with tumorigenicity in an isogenic, progressive breast cancer cell model, providing direct evidence for the tumorigenic origin of pteridines. Objectives: This study sought to elucidate the pteridine biosynthetic pathway in a progressive breast cancer model via direct pteridine dosing to determine how pteridine metabolism changes with tumorigenicity. Methods: First, MCF10AT breast cancer cells were dosed individually with 15 pteridines to determine …

Construction And Demonstration Of A 6–18 Ghz Microwave Three-Wave Mixing Experiment Using Multiple Synchronized Arbitrary Waveform Generators, Nicole T. Moon, Klaus Woelk, Garry S. Grubbs

Chemistry Faculty Research & Creative Works

This manuscript details the construction and demonstration of the first known microwave three-wave mixing (M3WM) experiment utilizing multiple arbitrary waveform generators (AWGs) completely operable in the 6–18 GHz frequency range for use in chirality determination and quantification. Many M3WM techniques, which involve two orthogonal, subsequent Rabi π/2 and π microwave pulses, suffer from flexibility in pulse types and timings as well as frequency due to most instruments only using one, one-channel AWG and the M3WM probability decreasing with an increasing quantum number, J. In this work, we presented an M3WM instrument that allows that flexibility by introducing multiple, synchronized AWGs …

Theranostic Copolymers Neutralize Reactive Oxygen Species And Lipid Peroxidation Products For The Combined Treatment Of Traumatic Brain Injury, Aaron Priester, Richard Waters, Ashleigh Abbott, Krista Hilmas, Klaus Woelk, Hunter A. Miller, Aria W. Tarudji, Connor C. Gee, Brandon Mcdonald, Forrest M. Kievit, Anthony J. Convertine

Chemistry Faculty Research & Creative Works

Traumatic brain injury (TBI) results in the generation of reactive oxygen species (ROS) and lipid peroxidation product (LPOx), including acrolein and 4-hydroxynonenal (4HNE). The presence of these biochemical derangements results in neurodegeneration during the secondary phase of the injury. The ability to rapidly neutralize multiple species could significantly improve outcomes for TBI patients. However, the difficulty in creating therapies that target multiple biochemical derangements simultaneously has greatly limited therapeutic efficacy. Therefore, our goal was to design a material that could rapidly bind and neutralize both ROS and LPOx following TBI. To do this, a series of thiol-functionalized biocompatible copolymers based …

Quantification Of Silver Nanoparticle Interactions With Yeast Saccharomyces Cerevisiae Studied Using Single-Cell Icp-Ms, Lindsey Rasmussen, Honglan Shi, Wenyan Liu, Katie Shannon

Chemistry Faculty Research & Creative Works

Silver nanoparticles (AgNPs) have been used in many fields due to their anticancer, antimicrobial, and antiviral potential. Single-cell ICP-MS (SC-ICP-MS) is an emerging technology that allows for the rapid characterization and quantification of a metal analyte across a cell population in a single analysis. In this study, a new rapid and sensitive SC-ICP-MS method was developed to quantitatively study the interactions of AgNPs with yeast Saccharomyces cerevisiae. The method can quantify the cell concentration, silver concentration per cell, and profile the nanoparticle distribution in a yeast cell population. AgNP dosing time, concentration, and AgNP size were quantitatively evaluated for their …

Thiol Antioxidants Protect Human Lens Epithelial (Hle B-3) Cells Against Tert-Butyl Hydroperoxide-Induced Oxidative Damage And Cytotoxicity, Annalise Pfaff, Anna Chernatynskaya, Hannah Vineyard, Nuran Ercal

Chemistry Faculty Research & Creative Works

Oxidative damage to lens epithelial cells plays an important role in the development of age-related cataract, and the health of the lens has important implications for overall ocular health. As a result, there is a need for effective therapeutic agents that prevent oxidative damage to the lens. Thiol antioxidants such as tiopronin or N-(2-mercaptopropionyl)glycine (MPG), N-acetylcysteine amide (NACA), N-acetylcysteine (NAC), and exogenous glutathione (GSH) may be promising candidates for this purpose, but their ability to protect lens epithelial cells is not well understood. The effectiveness of these compounds was compared by exposing human lens epithelial cells (HLE B-3) to the …

Transition Metal‐Catalyzed And Mao‐Assisted Olefin Polymerization. Cyclic Isomers Of Sinn’S Dimer Are Excellent Ligands In Iron Complexes And Great Methylating Reagents, Kaidi Yang, Rainer Glaser

Chemistry Faculty Research & Creative Works

Methylaluminoxane (MAO) is the most commonly used co‐catalyst for transition metalcatalyzed olefin polymerization, but the structures of MAO species and their catalytic functions remain topics of intensive study. We are interested in MAO‐assisted polymerization with catalysts L(R₂)FeCl₂ (L = tridentate pyridine‐2,6‐diyldimethanimine; imine‐R = Me, Ph). It is our hypothesis that the MAO species is not merely enabling Fe−Me bond formation but functions as an integral part of the active catalyst, a MAO adduct of the Fe‐precatalyst [L(R₂)FeCl]⁺. In this paper, we explored the possible structures of acyclic and cyclic MAO species and their …

Noninvasive Detection, Tracking, And Characterization Of Aerogel Implants Using Diagnostic Ultrasound, Sagar Ghimire, Martina Rodriguez Sala, Swetha Chandrasekaran, Grigorios Raptopoulos, Marcus Worsley, Patrina Paraskevopoulou, Nicholas Leventis, Firouzeh Sabri

Chemistry Faculty Research & Creative Works

Medical implants are routinely tracked and monitored using different techniques, such as MRI, X‐ray, and ultrasound. Due to the need for ionizing radiation, the two former methods pose a significant risk to tissue. Ultrasound imaging, however, is non‐invasive and presents no known risk to human tissue. Aerogels are an emerging material with great potential in biomedical implants. While qualitative observation of ultrasound images by experts can already provide a lot of infor-mation about the implants and the surrounding structures, this paper describes the development and study of two simple B‐Mode image analysis techniques based on attenuation measurements and echogenicity comparisons, …

Multi-Walled Carbon Nanotube Supported Manganese Selenide As A Highly Active Bifunctional Oer And Orr Electrocatalyst, Harish Singh, Mckenzie Marley-Hines, Shatadru Chakravarty, Manashi Nath

Chemistry Faculty Research & Creative Works

Transition metal selenides have attracted intensive interest as cost-effective electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) because of the continuous thrust in sustainable energy conversion. In this article a Mn-based bifunctional electrocatalyst, MnSe, has been identified which shows efficient OER and ORR activity in alkaline medium. The catalytic activity could be further enhanced by using multiwalled carbon nanotubes (MWCNTs) which increases the charge transfer and electronic conductivity of the catalyst composite. This MnSe@MWCNT catalyst composite exhibits a very low overpotential of 290 mV at 10 mA cm⁻², which outperforms state-of-the-art RuO₂ as …

Epitaxial Electrodeposition Of Hole Transport Cuscn Nanorods On Au(111) At The Wafer Scale And Lift-Off To Produce Flexible And Transparent Foils, Bin Luo, Avishek Banik, Eric W. Bohannan, Jay A. Switzer

Chemistry Faculty Research & Creative Works

The wide bandgap p-type metal pseudohalide semiconductor copper(I) thiocyanate (CuSCN) can serve as a transparent hole transport layer in various opto-electronic applications such as perovsksite and organic solar cells and light-emitting diodes. The material deposits as one-dimensional CuSCN nanorod arrays, which are advantageous due to their high surface area and good charge transport properties. However, the growth of high-quality epitaxial CuSCN nanorods has remained a challenge. Here, we introduce a low cost and highly scalable room temperature procedure for producing epitaxial CuSCN nanorods on Au(111) by an electrochemical method. Epitaxial CuSCN grows on Au(111) with a high degree of in-plane …

Special Issue: Microbiota-Gut-Brain Axis, Mark Obrenovich, Prakash Reddy

Chemistry Faculty Research & Creative Works

No abstract provided.

A Novel Branched Polymer Gel System With Delayed Gelation Property For Conformance Control, Tao Song, Qi Feng, Thomas P. Schuman, Jie Cao, Baojun Bai

Chemistry Faculty Research & Creative Works

Excessive water production from oil reservoirs not only affects the economical production of oil, but it also results in serious environmental concerns. Polymer gels have been widely applied to decrease water production and thus improve oil production. However, traditional polymer gels such as partially hydrolyzed polyacrylamide (HPAM)/chromium (III) gel systems usually have a short gelation time and cannot meet the requirement of some conformance control projects. This paper introduces a novel polymer gel system of which crosslinking time can be significantly delayed. A branched polymer grafted from arginine by the surface initiation method is synthesized as the backbone, chromium acetate …

Collisional Excitation And Non-Lte Modeling Of Interstellar Chiral Propylene Oxide, Karlis Dzenis, Alexandre Faure, B. A. Mcguire, A. J. Remijan, P. J. Dagdigian, C. Rist, Richard Dawes, Ernesto Quintas-Sánchez, F. Lique, M. Hochlaf

Chemistry Faculty Research & Creative Works

The first set of theoretical rotational cross sections for propylene oxide (CH₃CHCH₂O) colliding with cold He atoms has been obtained at the full quantum level using a high-accuracy potential energy surface. By scaling the collision reduced mass, rotational rate coefficients for collisions with para-H₂ are deduced in the temperature range 5-30 K. These collisional coefficients are combined with radiative data in a non-LTE radiative transfer model in order to reproduce observations of propylene oxide made toward the Sagittarius B2(N) molecular cloud with the Green Bank and Parkes radio telescopes. The three detected absorption lines are …

Collisional Excitation And Non-Lte Modeling Of Interstellar Chiral Propylene Oxide, Karlis Dzenis, Alexandre Faure, B. A. Mcguire, A. J. Remijan, P. J. Dagdigian, C. Rist, Richard Dawes, Ernesto Quintas-Sánchez, F. Lique, M. Hochlaf

Chemistry Faculty Research & Creative Works

The first set of theoretical rotational cross sections for propylene oxide (CH₃CHCH₂O) colliding with cold He atoms has been obtained at the full quantum level using a high-accuracy potential energy surface. By scaling the collision reduced mass, rotational rate coefficients for collisions with para-H2 are deduced in the temperature range 5-30 K. These collisional coefficients are combined with radiative data in a non-LTE radiative transfer model in order to reproduce observations of propylene oxide made toward the Sagittarius B2(N) molecular cloud with the Green Bank and Parkes radio telescopes. The three detected absorption lines are found …

Noninvasive Detection, Tracking, And Characterization Of Aerogel Implants Using Diagnostic Ultrasound, Sagar Ghimire, Martina Rodriguez Sala, Swetha Chandrasekaran, Grigorios Raptopoulos, Marcus Worsley, Patrina Paraskevopoulou, Nicholas Leventis, Firouzeh Sabri

Chemistry Faculty Research & Creative Works

Medical implants are routinely tracked and monitored using different techniques, such as MRI, X‐ray, and ultrasound. Due to the need for ionizing radiation, the two former methods pose a significant risk to tissue. Ultrasound imaging, however, is non‐invasive and presents no known risk to human tissue. Aerogels are an emerging material with great potential in biomedical implants. While qualitative observation of ultrasound images by experts can already provide a lot of infor-mation about the implants and the surrounding structures, this paper describes the development and study of two simple B‐Mode image analysis techniques based on attenuation measurements and echogenicity comparisons, …

Special Issue: Microbiota–Gut–Brain Axis, Mark Obrenovich, V. (Prakash) Reddy

Chemistry Faculty Research & Creative Works

No abstract provided.

The Molecular Structure And Curious Motions In 1,1-Difluorosilacyclopent-3-Ene And Silacyclopent-3-Ene As Determined By Microwave Spectroscopy And Quantum Chemical Calculations, Thomas M.C. Mcfadden, Nicole Moon, Frank E. Marshall, Amanda J. Duerden, Esther J. Ocola, Jaan Laane, Gamil A. Guirgis, Garry S. Grubbs

Chemistry Faculty Research & Creative Works

The molecules 1,1-difluorosilacyclopent-3-ene (3SiCPF2) and silacyclopent-3-ene (3SiCP) have been synthesized and studied using chirped pulse, Fourier transform microwave (CP-FTMW) spectroscopy. For 3SiCP this is the first ever microwave study of the molecule and, for 3SiCPF2, the spectra reported in this work have been combined with that of previous work in a global fit. The spectra of each contain splitting which has been fit using a Hamiltonian consisting of semirigid and Coriolis coupling parameters. A refit of the original 3SiCPF2 work was also carried out. All fits and approaches are reported. Analyses of the spectra provide evidence that the molecule is …

Polybenzodiazine Aerogels: All-Nitrogen Analogues Of Polybenzoxazines Synthesis, Characterization, And High-Yield Conversion To Nanoporous Carbons, Vaibhav A. Edlabadkar, Saidulu Gorla, Rushi U. Soni, A. B.M.Shaheen Ud Doulah, Joseph Gloriod, Samuel Hackett, Nicholas Leventis, Chariklia Sotiriou-Leventis

Chemistry Faculty Research & Creative Works

Tetrahydroquinazoline (THQ) was designed as an all-nitrogen analogue of main-stream benzoxazine monomers. THQ solutions in DMF gelled at 100 °C via HCl-catalyzed ring-opening polymerization to polybenzodiazine (PBDAZ) wet gels, which were dried in an autoclave with supercritical fluid CO₂ to aerogels. These as-prepared PBDAZ-100 aerogels undergo ring-fusion aromatization at 240 °C under O₂. This oxidized form is referred to as PBDAZ-240. Chemical identification of PBDAZ-100 and PBDAZ-240 relied on consideration of all nine possible polymerization pathways, in combination with elemental analysis, infrared and solid-state 13C NMR spectroscopy, and 15N NMR spectroscopy of aerogels from the selectively 15N-enriched …

Solvation Of Isoelectronic Halide And Alkali Metal Ions By Argon Atoms, Carly A. Rock, Sarah N. Arradondo, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

This work systematically examines the interactions of alkali metal cations and their isoelectronic halide counterparts with up to six solvating Ar atoms (M+Arn and X–Arn, where M = Li, Na, K, and Rb; X = H, F, Cl, and Br; and n = 1–6) via full geometry optimizations with the MP2 method and robust, correlation-consistent quadruple-ζ (QZ) basis sets. 116 unique M+Arn and X–Arn stationary points have been characterized on the MP2/QZ potential energy surface. To the best of our knowledge, approximately two dozen of these stationary points have been reported here for the first time. Some of these new …

Super-Adsorbent Hydrogels For Removal Of Methylene Blue From Aqueous Solution: Dye Adsorption Isotherms, Kinetics, And Thermodynamic Properties, Buddhabhushan Salunkhe, Thomas P. Schuman

Chemistry Faculty Research & Creative Works

Removal of dyes through adsorption from wastewater has gained substantial interest in recent years, especially in development of hydrogel-based adsorbents, owing to their easy use and economical nature. The aim of the present study was to design a super-adsorbent hydrogel based on sodium styrene sulfonate (NaSS) monomer for removal of dyes like methylene blue (MB). NaSS displays both an aromatic ring and strongly ionic group in its monomer structure that can enhance adsorption capacity. Poly (sodium styrene sulfonate-co-dimethylacrylamide) hydrogels were prepared by solution free radical polymerization using gelatin meth acryloyl (GelMA) as crosslinker, creating a highly porous, three-dimensionally crosslinked polymer …

Calibration Of Gas Flow Meters Using Choked Flow And An Evacuated Vessel, Max B. Trueblood, Otmar Schmid, Nicholas Altese, Christian J. Hurst, Wenyan Liu, Teresa Gelles, Steven C. Achterberg, Philip D. Whitefield, Donald E. Hagen

Chemistry Faculty Research & Creative Works

The measurement of gas flow rates is of great importance in a wide range of modern technologies. This paper introduces a simple, yet accurate technique for in-house calibration of gas FMs (mass and volumetric) even under harsh environmental conditions such as encountered during field measurement campaigns. The method requires only readily available, low cost components: a vessel of known volume, an air pump, a pressure sensor and a metal plate orifice or a needle valve to act as a CO. The unique property of choked flow in the CO is used here for flow calibration. In the method presented here …

Experimental Data On Water Soluble Polymers Thermal And Hydrolytic Stability, Reactivity Ratios Of Monomers And Frr Calculation For Thermally Stable Preformed Particle Gels Therefrom, Buddhabhushan Salunkhe, Thomas P. Schuman, Ali Al Brahim, Baojun Bai

Chemistry Faculty Research & Creative Works

Experimental data on water soluble polymer thermal and hydrolytic stability in acidic, neutral and basic pH conditions in aqueous solution is presented. Thermal and hydrolytic stability of polymer aqueous solutions were monitored in variable pH medium by aging at 130 °C temperature for different aging time. Polymer viscosity measurements were performed periodically for 3 months. Furthermore, this data can serve as a basis of monomer selection for thermally stable hydrogels for applications like oil recovery, hydrogel coatings for steam sterilized medical devices and other applications. Reactivity ratios were determined for monomers associated to the most stable polymers using ¹H …

Preparation And Pharmacokinetic Characterization Of An Anti-Virulence Compound Nanosuspensions, Nan Wang, Feng Qi, Xiaolong He, Honglan Shi, David W. Anderson, Hao Li, Hongmin Sun

Chemistry Faculty Research & Creative Works

Antibiotic resistance has become a worldwide public health threat due to the rapid evolu-tion and spread of antibiotic-resistant bacteria. CCG-211790 is a novel anti-virulence compound that does not kill bacteria but could ameliorate human diseases by inhibiting expression of virulence factors, thereby applying less selection pressure for antibiotic resistance. However, its potential clinical use is restricted because of its poor aqueous solubility, resulting in formulation challenges. Nanosuspension technology is an effective way to circumvent this problem. Nanosuspensions of CCG-211790 with two different particle sizes, NanoA (315 ± 6 nm) and NanoB (915 ± 24 nm), were prepared using an antisolvent …

Characterization Of A Nitro-Forming Enzyme Involved In Fosfazinomycin Biosynthesis, Hannah Valentino, Pablo Sobrado

Chemistry Faculty Research & Creative Works

N-hydroxylating monooxygenases (NMOs) are a subclass of flavin-dependent enzymes that hydroxylate nitrogen atoms. Recently, unique NMOs that perform multiple reactions on one substrate molecule have been identified. Fosfazinomycin M (FzmM) is one such NMO, forming nitrosuccinate from aspartate (Asp) in the fosfazinomycin biosynthetic pathway in someStreptomycessp. This work details the biochemical and kinetic analysis of FzmM. Steady-state kinetic investigation shows that FzmM performs a coupled reaction with Asp (kcat, 3.0 ± 0.01 s-1) forming nitrosuccinate, which can be converted to fumarate and nitrite by the action of FzmL. FzmM displays a 70-fold higherkcat/KMvalue for NADPH compared to NADH and has …

Genotype, Age, Genetic Background, And Sex Influence Epha2-Related Cataract Development In Mice, Alpana Dave, Jamie E. Craig, Mohammad Alamein, Karina Skrzypiec, Justin Beltz, Annalise Pfaff, Kathryn P. Burdon, Nuran Ercal, Robb U. De Iongh, Shiwani Sharma

Chemistry Faculty Research & Creative Works

PURPOSE. Age-related cataract is the leading cause of blindness worldwide. Variants in the EPHA2 gene increase the disease risk, and its knockout in mice causes cataract. We investigated whether age, sex, and genetic background, risk factors for age-related cataract, and Epha2 genotype influence Epha2-related cataract development in mice.

METHODS. Cataract development was monitored in Epha2⁺/⁺, Epha2^+/-, and Epha2^-/- mice (Epha2^{Gt(KST085)Byg}) on C57BL/6J and FVB:C57BL/6J (50:50) backgrounds. Cellular architecture of lenses, endoplasmic reticulum (ER) stress, and redox state were determined using histological, molecular, and analytical techniques.

RESULTS. Epha2^-/- and Epha2^{+/- …}

Torsional Profiles Of Thiophene And Furan Oligomers: Probing The Effects Of Heterogeneity And Chain Length, Morgan A. Perkins, Laura M. Cline, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

A systematic analysis of the torsional profiles of 55 unique oligomers composed of two to four thiophene and/or furan rings (n = 2 to 4) has been conducted using three density functional theory (DFT) methods along with MP2 and three different coupled-cluster methods. Two planar or quasi-planar minima were identified for each n = 2 oligomer system. In every case, the torsional angle (τ) between the heteroatoms about the carbon-carbon bond connecting the two rings is at or near 180° for the global minimum and 0° for the local minimum, referred to as anti and syn conformations, respectively. These oligomers …

Structural And Biochemical Characterization Of The Flavin-Dependent Siderophore-Interacting Protein From Acinetobacter Baumannii, Hannah Valentino, David A. Korasick, Tabbetha J. Bohac, Justin A. Shapiro, Timothy A. Wencewicz, John J. Tanner, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Acinetobacter baumannii is an opportunistic pathogen with a high mortality rate due to multi-drug-resistant strains. The synthesis and uptake of the iron-chelating siderophores acinetobactin (Acb) and preacinetobactin (pre-Acb) have been shown to be essential for virulence. Here, we report the kinetic and structural characterization of BauF, a flavin-dependent siderophore-interacting protein (SIP) required for the reduction of Fe (III) bound to Acb/pre-Acb and release of Fe(II). Stopped-flow spectrophotometric studies of the reductive half-reaction show that BauF forms a stable neutral flavin semiquinone intermediate. Reduction with NAD(P)H is very slow (kobs, 0.001 s-1) and commensurate with the rate of reduction by photobleaching, …