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- Butyl rubber (2)
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- Chemoenzymatic (1)
- Chirality (1)
- Cholesterol (1)
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- Reichardt’s dye (1)
- Siloxane (1)
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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Vitamin E Circular Dichroism Studies: Insights Into Conformational Changes Induced By The Solvent’S Polarity, Drew Marquardt, Brad J. Van Oosten, Mikel Ghelfi, Jeffrey Atkinson, Thad A. Harroun
Vitamin E Circular Dichroism Studies: Insights Into Conformational Changes Induced By The Solvent’S Polarity, Drew Marquardt, Brad J. Van Oosten, Mikel Ghelfi, Jeffrey Atkinson, Thad A. Harroun
Chemistry and Biochemistry Publications
We used circular dichroism (CD) to study differences in CD spectra between α-, δ-, and methylated-α-tocopherol in solvents with different polarities. CD spectra of the different tocopherol structures differ from each other in intensity and peak locations, which can be attributed to chromanol substitution and the ability to form hydrogen bonds. In addition, each structure was examined in different polarity solvents using the Reichardt index—a measure of the solvent’s ionizing ability, and a direct measurement of solvent–solute interactions. Differences across solvents indicate that hydrogen bonding is a key contributor to CD spectra at 200 nm. These results are a first …
Morphology-Induced Defects Enhance Lipid Transfer Rates, Yan Xia, Kamil Charubin, Drew Marquardt, Frederick A. Heberle, John Katsaras, Jianhui Tian, Xiaolin Cheng, Ying Liu, Mu Ping Nieh
Morphology-Induced Defects Enhance Lipid Transfer Rates, Yan Xia, Kamil Charubin, Drew Marquardt, Frederick A. Heberle, John Katsaras, Jianhui Tian, Xiaolin Cheng, Ying Liu, Mu Ping Nieh
Chemistry and Biochemistry Publications
Molecular transfer between nanoparticles has been considered to have important implications regarding nanoparticle stability. Recently, the interparticle spontaneous lipid transfer rate constant for discoidal bicelles was found to be very different from spherical, unilamellar vesicles (ULVs). Here, we investigate the mechanism responsible for this discrepancy. Analysis of the data indicates that lipid transfer is entropically favorable, but enthalpically unfavorable with an activation energy that is independent of bicelle size and long- to short-chain lipid molar ratio. Moreover, molecular dynamics simulations reveal a lower lipid dissociation energy cost in the vicinity of interfaces ("defects") induced by the segregation of the long- …
Cholesterol's Location In Lipid Bilayers, Drew Marquardt, Norbert Kučerka, Stephen R. Wassall, Thad A. Harroun, John Katsaras
Cholesterol's Location In Lipid Bilayers, Drew Marquardt, Norbert Kučerka, Stephen R. Wassall, Thad A. Harroun, John Katsaras
Chemistry and Biochemistry Publications
It is well known that cholesterol modifies the physical properties of lipid bilayers. For example, the much studied liquid-ordered Lo phase contains rapidly diffusing lipids with their acyl chains in the all trans configuration, similar to gel phase bilayers. Moreover, the Lo phase is commonly associated with cholesterol-enriched lipid rafts, which are thought to serve as platforms for signaling proteins in the plasma membrane. Cholesterol's location in lipid bilayers has been studied extensively, and it has been shown – at least in some bilayers – to align differently from its canonical upright orientation, where its hydroxyl group is in the …
Insights From Molecular Dynamics On Substrate Binding And Effects Of Active Site Mutations In Delta1-Pyrroline-5-Carboxylate Dehydrogenase, Bogdan F. Ion, Mohamed M. Aboelnga, James W. Gauld
Insights From Molecular Dynamics On Substrate Binding And Effects Of Active Site Mutations In Delta1-Pyrroline-5-Carboxylate Dehydrogenase, Bogdan F. Ion, Mohamed M. Aboelnga, James W. Gauld
Chemistry and Biochemistry Publications
The NAD+-dependent enzyme, 1-pyrroline-5-carboxylate dehydrogenase (P5CDH), has an important role in proline and hydroxyproline catabolism for humans. Specifically, this aldehyde dehydrogenase is responsible for the oxidation of both L-glutamate- -semialdehyde (GSA) and 4-erythro-hydroxy-L-glutamate- -semialdehyde (4-OH-GSA) to their respective L-glutamate product forms. We have performed a detailed molecular dynamics (MD) study of both the reactant and product complex structures of P5CDH to gain insights into ligand binding (i.e., GSA, 4-OH-GSA, NAD+, GLU) in the active site. Moreover, our investigations were further extended to examine the structural impact of S352L, S352A, and E314A mutations on the deficiency in the P5CDH enzymatic activity. …
Elastomers: Reinventing Butyl Rubber For Stretchable Electronics (Adv. Funct. Mater. 29/2016), Akhil Vohra, Heather L. Filiatrault, Stanley D. Amyotte, R. Stephen Carmichael, Natalie D. Suhan, Conrad Siegers, Lorenzo Ferrari, Gregory J.E. Davidson, Tricia Breen Carmichael
Elastomers: Reinventing Butyl Rubber For Stretchable Electronics (Adv. Funct. Mater. 29/2016), Akhil Vohra, Heather L. Filiatrault, Stanley D. Amyotte, R. Stephen Carmichael, Natalie D. Suhan, Conrad Siegers, Lorenzo Ferrari, Gregory J.E. Davidson, Tricia Breen Carmichael
Chemistry and Biochemistry Publications
No abstract provided.
Polyisobutylene-Paclitaxel Conjugates With Pendant Carboxylic Acids And Polystyrene Chains: Towards Multifunctional Stent Coatings With Slow Drug Release, John F. Trant, Mahmoud M. Abd Rabo Moustafa, Inderpreet Sran, Elizabeth R. Gillies
Polyisobutylene-Paclitaxel Conjugates With Pendant Carboxylic Acids And Polystyrene Chains: Towards Multifunctional Stent Coatings With Slow Drug Release, John F. Trant, Mahmoud M. Abd Rabo Moustafa, Inderpreet Sran, Elizabeth R. Gillies
Chemistry and Biochemistry Publications
Drug-eluting stents are used in the treatment of atherosclerosis, where the incorporation of anti-proliferative or anti-inflammatory drugs decreases the rate of restenosis, the recurrence of artery narrowing. However, these stents can suffer from limitations such as drug depletion and delamination of the drug-eluting coating from the stent surface. Described here is an approach aimed at addressing these issues. Starting from a maleic anhydride adduct of polyisobutylene (PIB) prepared from butyl rubber, ring opening using paclitaxel (PTX) or a combination of PTX and polystyrene (PS) afforded covalent conjugates of PTX and PIB or PIB-PS graft copolymers bearing pendant carboxylic acids. When …
A Chemoenzymatic Route To Chiral Siloxanes, Ravi Naoum, Jacqueline P. Séguin, John F. Trant, Mark B. Frampton, Tomáš Hudlický, Paul M. Zelisko
A Chemoenzymatic Route To Chiral Siloxanes, Ravi Naoum, Jacqueline P. Séguin, John F. Trant, Mark B. Frampton, Tomáš Hudlický, Paul M. Zelisko
Chemistry and Biochemistry Publications
An approach employing two enzymes—toluene dioxygenase and immobilized lipase B from Candida antarctica (N435)—was explored as a potential biocatalytic method for the coupling of chiral diols with siloxane species. Analysis of reaction mixtures using1H NMR spectroscopy suggested that up to 66% consumption of the siloxane starting materials had occurred. Oligomeric species were observed and chiral products from the coupling of a cyclic diol with a siloxane molecule were isolated and characterized by MALDI-ToF MS and GPC. Immobilized lipases from Rhizomucor miehei and Thermomyces lanuginosus were also explored as potential catalysts for the coupling reactions, however, their use only returned starting …
Lipid Bilayer Thickness Determines Cholesterols Location In Model Membranes, Drew Marquardt, Frederick A. Heberle, Denise V. Greathouse, Roger E. Koeppe, Robert F. Standaert, Brad J. Van Oosten, Thad A. Harroun, Jacob J. Kinnun, Justin A. Williams, Stephen R. Wassall, John Katsaras
Lipid Bilayer Thickness Determines Cholesterols Location In Model Membranes, Drew Marquardt, Frederick A. Heberle, Denise V. Greathouse, Roger E. Koeppe, Robert F. Standaert, Brad J. Van Oosten, Thad A. Harroun, Jacob J. Kinnun, Justin A. Williams, Stephen R. Wassall, John Katsaras
Chemistry and Biochemistry Publications
Cholesterol is an essential biomolecule of animal cell membranes, and an important precursor for the biosynthesis of certain hormones and vitamins. It is also thought to play a key role in cell signaling processes associated with functional plasma membrane microdomains (domains enriched in cholesterol), commonly referred to as rafts. In all of these diverse biological phenomena, the transverse location of cholesterol in the membrane is almost certainly an important structural feature. Using a combination of neutron scattering and solid-state2H NMR, we have determined the location and orientation of cholesterol in phosphatidylcholine (PC) model membranes having fatty acids of different lengths …