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Full-Text Articles in Physics
Sucralose Destabilization Of Protein Structure, Christina M. Othon
Sucralose Destabilization Of Protein Structure, Christina M. Othon
Christina M Othon
Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence …
Electron Irradiation Effects On Ferroelectric Copolymer Langmuir-Blodgett Films, Christina M. Othon, Stephen Ducharme
Electron Irradiation Effects On Ferroelectric Copolymer Langmuir-Blodgett Films, Christina M. Othon, Stephen Ducharme
Christina M Othon
The effect of irradiation on the ferroelectric properties of Langmuir-Blodgett films of the copolymer poly(vinylidene fluoride-trifluorethelene) is investigating using 1.26 MeV electrons with dosages from 16 to 110 Mrad. Irradiation causes a systematic decrease in the phase transition temperature, coercive field and polarization of these thin films.
Hydration Dynamics At Fluorinated Protein Surfaces, Oh-Hoon Kwon, Tae Hyeon Yoo, Christina M. Othon, James A. Van Deventer, David A. Tirrell, Ahmed H. Zewail
Hydration Dynamics At Fluorinated Protein Surfaces, Oh-Hoon Kwon, Tae Hyeon Yoo, Christina M. Othon, James A. Van Deventer, David A. Tirrell, Ahmed H. Zewail
Christina M Othon
Water-protein interactions dictate many processes crucial to protein function including folding, dynamics, interactions with other biomolecules, and enzymatic catalysis. Here we examine the effect of surface fluorination on water-protein interactions. Modification of designed coiled-coil proteins by incorporation of 5,5,5-trifluoroleucine or (4S)-2-amino-4-methylhexanoic acid enables systematic examination of the effects of side-chain volume and fluorination on solvation dynamics. Using ultrafast fluorescence spectroscopy, we find that fluorinated side chains exert electrostatic drag on neighboring water molecules, slowing water motion at the protein surface.
Charge Transfer Assisted By Collective H-Bonding Network Dynamics, Omar F. Mohammed, Christina M. Othon, Oh-Hoon Kwon, Ahmed H. Zewail
Charge Transfer Assisted By Collective H-Bonding Network Dynamics, Omar F. Mohammed, Christina M. Othon, Oh-Hoon Kwon, Ahmed H. Zewail
Christina M Othon
Although there have been numerous studies of solvation, the role of solvent specific and collective interactions, especially for charge-transfer processes, remains difficult to unravel. Here, we report, using femtosecond fluorescence up-conversion and steady-state spectroscopic measurements, studies of well-designed single-sited formylperylene (FPe) in binary solvents. One of the solvents (methanol, MOH) can selectively hydrogen (H) bond to the carbonyl (C=O) site, while the other (acetonitrile, ACN) cannot, but both have similar polarity ( for MOH and for ACN). The results reveal that ultrafast charge transfer from the perylene unit to the carbonyl group of FPe is facilitated by site-specific H-bonding interactions …
Solvation In Protein (Un)Folding: Effect Of Local And Bulk Dynamics In The Melittin Tetramer-Monomer Transition, Christina M. Othon, Oh-Hoon Kwon, Milo M. Lin, Ahmed H. Zewail
Solvation In Protein (Un)Folding: Effect Of Local And Bulk Dynamics In The Melittin Tetramer-Monomer Transition, Christina M. Othon, Oh-Hoon Kwon, Milo M. Lin, Ahmed H. Zewail
Christina M Othon
Protein structural integrity and flexibility are intimately tied to solvation. Here we examine the effect that changes in bulk and local solvent properties have on protein structure and stability. We observe the change in solvation of an unfolding of the protein model, melittin, in the presence of a denaturant, trifluoroethanol. The peptide system displays a well defined transition in that the tetramer unfolds without disrupting the secondary or tertiary structure. In the absence of local structural perturbation, we are able to reveal exclusively the role of solvation dynamics in protein structure stabilization and the (un)folding pathway. A sudden retardation in …