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Article: Pf bacteriophages hinder sputum antibiotic diffusion via electrostatic binding.

Chen, Qingquan / Cai, Pam / Chang, Tony Hong Wei / Burgener, Elizabeth / Kratochvil, Michael J / Gupta, Aditi / Hargil, Aviv / Secor, Patrick R / Nielsen, Josefine Eilsø / Barron, Annelise E / Milla, Carlos / Heilshorn, Sarah C / Spakowitz, Andy / Bollyky, Paul L

bioRxiv : the preprint server for biology

2024

Abstract: Despite great progress in the field, ... ...

Abstract	Despite great progress in the field, chronic
Language	English
Publishing date	2024-03-10
Publishing country	United States
Document type	Preprint
DOI	10.1101/2024.03.10.584330
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Article ; Online: Evidence of a preferred kinetic pathway in the carnitine acetyltransferase reaction.

Kratochvil, Michael J / Balerud, Nick K / Schindler, Samantha J / Moxley, Michael A

Archives of biochemistry and biophysics

2020 Volume 691, Page(s) 108507

Abstract: Mammalian carnitine acetyltransferase (CrAT) is a mitochondrial enzyme that catalyzes the reversible transfer of an acetyl group from acetyl-CoA to carnitine. CrAT knockout studies have shown that this enzyme is critical to sustain metabolic flexibility, ...

Abstract	Mammalian carnitine acetyltransferase (CrAT) is a mitochondrial enzyme that catalyzes the reversible transfer of an acetyl group from acetyl-CoA to carnitine. CrAT knockout studies have shown that this enzyme is critical to sustain metabolic flexibility, or the ability to switch between different fuel types, an underlying theme of the metabolic syndrome. These recent physiological findings imply that CrAT dysfunction, or its catalytic impairment, may lead to disease. To gain insight into the CrAT kinetic mechanism, we conducted stopped-flow experiments in various enzyme substrate/product conditions and analyzed full progress curves by global fitting. Simultaneous mixing of both substrates with CrAT produced relatively fast kinetics that follows an ordered bi bi mechanism. A great preference for ordered binding is supported by stopped-flow double mixing experiments such that premixed CrAT with acetyl-CoA or CoA demonstrated a biphasic decrease in initial rate that produces about a 100-fold attenuation in catalysis. Double mixing experiments also revealed that the CrAT initial rate is inhibited by 50% in approximately 8 s by either acetyl-CoA or CoA premixing. Analysis of available CrAT structures support a substrate conformational change between acetyl-CoA/CoA binary versus ternary complexes. Additional viscosity-based kinetic experiments yielded strong evidence that product release is the rate limiting step in the CrAT-catalyzed reaction.
MeSH term(s)	Acetyl Coenzyme A/chemistry ; Acetyl Coenzyme A/metabolism ; Animals ; Carnitine/chemistry ; Carnitine/metabolism ; Carnitine O-Acetyltransferase/chemistry ; Carnitine O-Acetyltransferase/metabolism ; Catalysis ; Catalytic Domain ; Coenzyme A/chemistry ; Coenzyme A/metabolism ; Columbidae ; Crystallography, X-Ray ; Kinetics ; Mice ; Protein Binding
Chemical Substances	Acetyl Coenzyme A (72-89-9) ; Carnitine O-Acetyltransferase (EC 2.3.1.7) ; Carnitine (S7UI8SM58A) ; Coenzyme A (SAA04E81UX)
Language	English
Publishing date	2020-07-22
Publishing country	United States
Document type	Journal Article
ZDB-ID	523-x
ISSN	1096-0384 ; 0003-9861
ISSN (online)	1096-0384
ISSN	0003-9861
DOI	10.1016/j.abb.2020.108507
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Article ; Online: Size Effects of the Anions in the Ionothermal Synthesis of Carbon Nitride Materials.

Burmeister, David / Müller, Johannes / Plaickner, Julian / Kochovski, Zdravko / List-Kratochvil, Emil J W / Bojdys, Michael J

Chemistry (Weinheim an der Bergstrasse, Germany)

2022 Volume 28, Issue 33, Page(s) e202200705

Abstract: Semiconducting carbon nitride polymers are used in metal-free photocatalysts and in opto-electronic devices. Conventionally, they are obtained using thermal and ionothermal syntheses in inscrutable, closed systems and therefore, their condensation ... ...

Abstract	Semiconducting carbon nitride polymers are used in metal-free photocatalysts and in opto-electronic devices. Conventionally, they are obtained using thermal and ionothermal syntheses in inscrutable, closed systems and therefore, their condensation behavior is poorly understood. Here, the synthetic protocols and properties are compared for two types of carbon nitride materials - 2D layered poly(triazine imide) (PTI) and hydrogen-bonded melem hydrate - obtained from three low-melting salt eutectics taken from the systematic series of the alkali metal halides: LiCl/KCl, LiBr/KBr, and LiI/KI. The size of the anion plays a significant role in the formation process of the condensed carbon nitride polymers, and it suggests a strong templating effect. The smaller anions (chloride and bromide) become incorporated into triazine (C
Language	English
Publishing date	2022-05-02
Publishing country	Germany
Document type	Journal Article
ZDB-ID	1478547-X
ISSN	1521-3765 ; 0947-6539
ISSN (online)	1521-3765
ISSN	0947-6539
DOI	10.1002/chem.202200705
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Article: Evidence of a preferred kinetic pathway in the carnitine acetyltransferase reaction

Kratochvil, Michael J / Balerud, Nick K / Schindler, Samantha J / Moxley, Michael A

Archives of biochemistry and biophysics. 2020 Sept. 30, v. 691

2020

Abstract	Mammalian carnitine acetyltransferase (CrAT) is a mitochondrial enzyme that catalyzes the reversible transfer of an acetyl group from acetyl-CoA to carnitine. CrAT knockout studies have shown that this enzyme is critical to sustain metabolic flexibility, or the ability to switch between different fuel types, an underlying theme of the metabolic syndrome. These recent physiological findings imply that CrAT dysfunction, or its catalytic impairment, may lead to disease. To gain insight into the CrAT kinetic mechanism, we conducted stopped-flow experiments in various enzyme substrate/product conditions and analyzed full progress curves by global fitting. Simultaneous mixing of both substrates with CrAT produced relatively fast kinetics that follows an ordered bi bi mechanism. A great preference for ordered binding is supported by stopped-flow double mixing experiments such that premixed CrAT with acetyl-CoA or CoA demonstrated a biphasic decrease in initial rate that produces about a 100-fold attenuation in catalysis. Double mixing experiments also revealed that the CrAT initial rate is inhibited by 50% in approximately 8 s by either acetyl-CoA or CoA premixing. Analysis of available CrAT structures support a substrate conformational change between acetyl-CoA/CoA binary versus ternary complexes. Additional viscosity-based kinetic experiments yielded strong evidence that product release is the rate limiting step in the CrAT-catalyzed reaction.
Keywords	acetyl coenzyme A ; biophysics ; carnitine ; carnitine acetyltransferase ; catalytic activity ; enzyme substrates ; mammals ; metabolic syndrome ; mitochondria
Language	English
Dates of publication	2020-0930
Publishing place	Elsevier Inc.
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	523-x
ISSN	1096-0384 ; 0003-9861
ISSN (online)	1096-0384
ISSN	0003-9861
DOI	10.1016/j.abb.2020.108507
Database	NAL-Catalogue (AGRICOLA)

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Article: On the non-bonding valence band and the electronic properties of poly(triazine imide), a graphitic carbon nitride.

Burmeister, David / Eljarrat, Alberto / Guerrini, Michele / Röck, Eva / Plaickner, Julian / Koch, Christoph T / Banerji, Natalie / Cocchi, Caterina / List-Kratochvil, Emil J W / Bojdys, Michael J

Chemical science

2023 Volume 14, Issue 23, Page(s) 6269–6277

Abstract: Graphitic carbon nitrides are covalently-bonded, layered, and crystalline semiconductors with high thermal and oxidative stability. These properties make graphitic carbon nitrides potentially useful in overcoming the limitations of 0D molecular and 1D ... ...

Abstract	Graphitic carbon nitrides are covalently-bonded, layered, and crystalline semiconductors with high thermal and oxidative stability. These properties make graphitic carbon nitrides potentially useful in overcoming the limitations of 0D molecular and 1D polymer semiconductors. In this contribution, we study structural, vibrational, electronic and transport properties of nano-crystals of poly(triazine-imide) (PTI) derivatives with intercalated Li- and Br-ions and without intercalates. Intercalation-free poly(triazine-imide) (PTI-IF) is corrugated or AB stacked and partially exfoliated. We find that the lowest energy electronic transition in PTI is forbidden due to a non-bonding uppermost valence band and that its electroluminescence from the π-π* transition is quenched which severely limits their use as emission layer in electroluminescent devices. THz conductivity in nano-crystalline PTI is up to eight orders of magnitude higher than the macroscopic conductivity of PTI films. We find that the charge carrier density of PTI nano-crystals is among the highest of all known intrinsic semiconductors, however, macroscopic charge transport in films of PTI is limited by disorder at crystal-crystal interfaces. Future device applications of PTI will benefit most from single crystal devices that make use of electron transport in the lowest, π-like conduction band.
Language	English
Publishing date	2023-04-18
Publishing country	England
Document type	Journal Article
ZDB-ID	2559110-1
ISSN	2041-6539 ; 2041-6520
ISSN (online)	2041-6539
ISSN	2041-6520
DOI	10.1039/d3sc00667k
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Article: Filamentous Bacteriophages and the Competitive Interaction between Pseudomonas aeruginosa Strains under Antibiotic Treatment: a Modeling Study.

Pourtois, Julie D / Kratochvil, Michael J / Chen, Qingquan / Haddock, Naomi L / Burgener, Elizabeth B / De Leo, Giulio A / Bollyky, Paul L

mSystems

2021 Volume 6, Issue 3, Page(s) e0019321

Abstract: Pseudomonas aeruginosa ( ...

Abstract	Pseudomonas aeruginosa (
Language	English
Publishing date	2021-06-22
Publishing country	United States
Document type	Journal Article
ISSN	2379-5077
ISSN	2379-5077
DOI	10.1128/mSystems.00193-21
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Article ; Online: Amine-Reactive Azlactone-Containing Nanofibers for the Immobilization and Patterning of New Functionality on Nanofiber-Based Scaffolds.

Kratochvil, Michael J / Carter, Matthew C D / Lynn, David M

ACS applied materials & interfaces

2017 Volume 9, Issue 11, Page(s) 10243–10253

Abstract: We report the design of amine-reactive polymer nanofibers and nonwoven reactive nanofiber mats fabricated by the electrospinning of azlactone-functionalized polymers. We demonstrate that randomly oriented nanofibers fabricated using a random copolymer of ...

Abstract	We report the design of amine-reactive polymer nanofibers and nonwoven reactive nanofiber mats fabricated by the electrospinning of azlactone-functionalized polymers. We demonstrate that randomly oriented nanofibers fabricated using a random copolymer of methyl methacrylate and 2-vinyl-4,4-dimethylazlactone contain intact and reactive azlactone groups that can be used to introduce new chemical functionality and modulate important interfacial properties of these materials (e.g., wetting behaviors) by postfabrication treatment with primary amine-based nucleophiles. The facile and "click-like" nature of these reactions permits functionalization under mild conditions without substantial changes to nanofiber or mat morphologies. This approach also enables the patterning of new functionality on mat-coated surfaces by treatment with bulk solutions of primary amines or by using methods such as microcontact printing. Further, these reactive mats can also, themselves, be contact-transferred or "printed" onto secondary surfaces by pressing them into contact with other amine-functionalized objects. Finally, we demonstrate that functionalization with hydrophobic amines can increase the stability of these materials in aqueous environments and yield hydrophobic nanofiber scaffolds useful for the design of "slippery" liquid-infused materials. The approaches reported here enable the introduction of new properties to reactive polymer mats after fabrication and, thus, reduce the need to synthesize individual functional polymers prior to electrospinning to achieve new properties. The azlactone chemistry used here broadens the scope of reactions that can be used to functionalize polymer nanofibers and is likely to prove general. We anticipate that this approach can be used with a range of amines or other nucleophiles (e.g., alcohols or thiols) to design nanofibers and reactive nanofiber-based materials with new physical properties, surface features, and behaviors that may be difficult to achieve by the direct electrospinning of conventional materials or other functional polymers.
Language	English
Publishing date	2017-03-22
Publishing country	United States
Document type	Journal Article
ISSN	1944-8252
ISSN (online)	1944-8252
DOI	10.1021/acsami.7b00219
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Article: Superhydrophobic polymer multilayers for the filtrationâ and absorptionâbased separation of oil/water mixtures

Kratochvil, Michael J / Uttam Manna / David M. Lynn

Journal of polymer science. 2017 Sept. 15, v. 55, no. 18

2017

Abstract	We report layerâbyâlayer approaches to the design of superhydrophobic and superoleophilic substrates for the filtrationâ or absorptionâbased separation of bulk oil from oil/water mixtures. Fabrication of covalently crossâlinked, nanoporous polymer multilayers on mesh substrates yielded superhydrophobic and superoleophilic porous media that allow oil to pass, but completely prevent the passage of bulk water. This approach can be used to promote the filtration of oil/water mixtures, and these filmâcoated substrates can be bent and physically manipulated without affecting oilâ and waterâwetting properties. Fabrication on threeâdimensional macroporous polymer pads yielded flexible objects that float on water and absorb oil at contaminated air/water interfaces. This approach permits oil to be recovered by squeezing or rinsing with solvent and the reuse of these materials without decreases in performance. These pads can also absorb oil from simulated seawater, brine, and other media representative of marine or industrial contexts where oil contamination can occur. Our results address issues associated with the design of polymerâbased coatings for the separation, removal, and collection of oil from oilâcontaminated water. With further development, this approach could provide lowâenergy alternatives to conventional remediation methods or yield new strategies that can be implemented in ways that are impractical using current technologies. Â© 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3127â3136
Keywords	air pollution ; chemical bonding ; coatings ; crosslinking ; filtration ; hydrophobicity ; nanopores ; oils ; polymers ; porous media ; remediation ; seawater ; solvents
Language	English
Dates of publication	2017-0915
Size	p. 3127-3136.
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ISSN	0887-624X
DOI	10.1002/pola.28691
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Nonwoven Polymer Nanofiber Coatings That Inhibit Quorum Sensing in Staphylococcus aureus: Toward New Nonbactericidal Approaches to Infection Control.

Kratochvil, Michael J / Yang, Tian / Blackwell, Helen E / Lynn, David M

ACS infectious diseases

2017 Volume 3, Issue 4, Page(s) 271–280

Abstract: We report the fabrication and biological evaluation of nonwoven polymer nanofiber coatings that inhibit quorum sensing (QS) and virulence in the human pathogen Staphylococcus aureus. Our results demonstrate that macrocyclic peptide 1, a potent and ... ...

Abstract	We report the fabrication and biological evaluation of nonwoven polymer nanofiber coatings that inhibit quorum sensing (QS) and virulence in the human pathogen Staphylococcus aureus. Our results demonstrate that macrocyclic peptide 1, a potent and synthetic nonbactericidal quorum sensing inhibitor (QSI) in S. aureus, can be loaded into degradable polymer nanofibers by electrospinning and that this approach can deposit QSI-loaded nanofiber coatings onto model nonwoven mesh substrates. The QSI was released over ∼3 weeks when these materials were incubated in physiological buffer, retained its biological activity, and strongly inhibited agr-based QS in a GFP reporter strain of S. aureus for at least 14 days without promoting cell death. These materials also inhibited production of hemolysins, a QS-controlled virulence phenotype, and reduced the lysis of erythrocytes when placed in contact with wild-type S. aureus growing on surfaces. This approach is modular and can be used with many different polymers, active agents, and processing parameters to fabricate nanofiber coatings on surfaces important in healthcare contexts. S. aureus is one of the most common causative agents of bacterial infections in humans, and strains of this pathogen have developed significant resistance to conventional antibiotics. The QSI-based strategies reported here thus provide springboards for the development of new anti-infective materials and novel treatment strategies that target virulence as opposed to growth in S. aureus. This approach also provides porous scaffolds for cell culture that could prove useful in future studies on the influence of QS modulation on the development and structure of bacterial communities.
MeSH term(s)	Anti-Bacterial Agents/chemistry ; Anti-Bacterial Agents/pharmacology ; Gene Expression Regulation, Bacterial/drug effects ; Hemolysin Proteins/metabolism ; Humans ; Macrocyclic Compounds/chemistry ; Macrocyclic Compounds/pharmacology ; Nanofibers/chemistry ; Polymers/chemistry ; Quorum Sensing/drug effects ; Staphylococcus aureus/drug effects ; Staphylococcus aureus/metabolism ; Staphylococcus aureus/pathogenicity ; Virulence/drug effects
Chemical Substances	Anti-Bacterial Agents ; Hemolysin Proteins ; Macrocyclic Compounds ; Polymers
Language	English
Publishing date	2017-02-20
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ISSN	2373-8227
ISSN (online)	2373-8227
DOI	10.1021/acsinfecdis.6b00173
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Article ; Online: Optimized Synthesis of Solution-Processable Crystalline Poly(Triazine Imide) with Minimized Defects for OLED Application.

Burmeister, David / Tran, Ha Anh / Müller, Johannes / Guerrini, Michele / Cocchi, Caterina / Plaickner, Julian / Kochovski, Zdravko / List-Kratochvil, Emil J W / Bojdys, Michael J

Angewandte Chemie (International ed. in English)

2021 Volume 61, Issue 3, Page(s) e202111749

Abstract: Poly(triazine imide) (PTI) is a highly crystalline semiconductor, and though no techniques exist that enable synthesis of macroscopic monolayers of PTI, it is possible to study it in thin layer device applications that are compatible with its ... ...

Abstract	Poly(triazine imide) (PTI) is a highly crystalline semiconductor, and though no techniques exist that enable synthesis of macroscopic monolayers of PTI, it is possible to study it in thin layer device applications that are compatible with its polycrystalline, nanoscale morphology. We find that the by-product of conventional PTI synthesis is a C-C carbon-rich phase that is detrimental for charge transport and photoluminescence. An optimized synthetic protocol yields a PTI material with an increased quantum yield, enabled photocurrent and electroluminescence. We report that protonation of the PTI structure happens preferentially at the pyridinic N atoms of the triazine rings, is accompanied by exfoliation of PTI layers, and contributes to increases in quantum yield and exciton lifetimes. This study describes structure-property relationships in PTI that link the nature of defects, their formation, and how to avoid them with the optical and electronic performance of PTI. On the basis of our findings, we create an OLED prototype with PTI as the active, metal-free material.
Language	English
Publishing date	2021-12-18
Publishing country	Germany
Document type	Journal Article
ZDB-ID	2011836-3
ISSN	1521-3773 ; 1433-7851
ISSN (online)	1521-3773
ISSN	1433-7851
DOI	10.1002/anie.202111749
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