Statistical thermodynamic consideration of solvent effects on conformational stability. Supermolecule-continuum model

Beveridge, David L.; Schnuelle, G. W.

doi:10.1021/j100613a015

Cited by 37 publications

(19 citation statements)

References 7 publications

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“…The concentrations of free sulfhydryl (−SH) groups in the skim milk samples before and after HHP treatment were determined using Ellman's reagent (5′,5‐dithiobis [2‐nitrobenzoic acid], DTNB; Sigma‐Aldrich). The changes in −SH groups were evaluated in triplicate according to the methods detailed in a previous report (Beveridge and Schnuelle ). The absorbance was measured at 412 nm on a UV/VIS spectrophotometer (Shanghai JINMI Science Instrument Co., Ltd., Shanghai, China) using the diluent buffer mixed with Ellman's reagent as a blank.…”

Section: Methodsmentioning

confidence: 99%

Inhibitor‐Assisted High‐Pressure Inactivation of Bacteria in Skim Milk

Liu

Sun

et al. 2017

Journal of Food Science

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The combined inactivation effects of high hydrostatic pressure (HHP) and antimicrobial compounds (potassium sorbate and ε-polylysine [ε-PL]) on 4 different bacterial strains present in skim milk and the effect of these treatments on milk quality were investigated in this study. HHP treatment at 500 MPa for 5 min reduced the populations of Escherichia coli, Salmonella enterica Typhimurium, Listeria monocytogenes, and Staphylococcus aureus from 6.5 log colony-forming units (CFUs) or higher to less than 1 log CFU/mL. Compared to HHP alone, HHP with potassium or ε-PL resulted in significantly higher reductions in the bacterial counts. After 5 min of treatment with HHP (500 MPa) and ε-PL (2 mg/mL), no growth of E. coli, S. enterica Typhimurium, or L. monocytogenes in skim milk was observed during 15 d of refrigerated storage (4 ± 1 °C). Scanning electron microscopy analysis revealed that the synergistic treatments caused more serious damage to the bacterial cell walls. Quality assessments of the treated samples indicated that the combined treatments did not influence the color, the turbidity, the concentrations of -SH group of the proteins, or the in vitro digestion patterns of the milk. This study demonstrates that HHP with potassium or ε-PL may be useful in the processing of milk or milk-containing foods.

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Section: Methodsmentioning

confidence: 99%

Inhibitor‐Assisted High‐Pressure Inactivation of Bacteria in Skim Milk

Liu

Sun

et al. 2017

Journal of Food Science

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“…Initially, bulk dielectric effects were investigated by a SCRF according to the continuum model 28–30 in the formulations suggested by Karelson and Zerner and colleagues 30, 31. In addition, NR was reoptimized with solvent molecules explicitly included in the input geometry according to the supermolecule model 32–34, and the number of solvent molecules coordinated to the solute varied from one to three. The following solvent molecules were investigated: ethanol, methanol, benzene, and chloroform.…”

Section: Experimental and Methodsmentioning

confidence: 99%

Investigation of the Nile Red spectra by semi‐empirical calculations and spectrophotometric measurements

Dias

Custódio

Pessine

2006

Int J of Quantum Chemistry

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ABSTRACT:The spectroscopic behavior of Nile Red (NR) in solutions was investigated by spectrophotometric measurements and was calculated with the semiempirical intermediate neglect of differential overlap for spectroscopy (INDO/S) method. Two parametrizations implemented, respectively, by Pople and by Da Motta and Zerner, were employed; the solvent effects were simulated according to the dielectric continuum model [self-consistent reaction field (SCRF)], as well as with the explicit inclusion of solvent molecules. The calculations simulated reasonably well the experimental spectra and the intense solvatochromism of NR because the dipole moments were calculated to be higher in the first excited state than in the ground state. In addition, INDO/S calculations were carried out for partially optimized twisted conformers, whose electron donor moiety was orthogonal to the aromatic acceptor one and charge transfer was observed for excited states known as twisted intramolecular charge-transfer (TICT) states. In polar media, INDO/SϩSCRF calculations drastically stabilized the TICT state, reducing its energy down to the first excited state. Despite this intense solute-solvent stabilization, it is still less stable than the first excited state of the nontwisted, fully optimized conformer, and the limitations of the semi-empirical methods could not predict its role, if any, on the spectroscopic behavior of NR, except for the fact that the solvatochromism was explained independent of its presence.

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“…This combined approach has been called a supermolecule-continuum model (Beveridge and Schnuelle, 1974), discrete-continuum model (Claverie et al, 1978), cluster-continuum model (Pliego and Riveros, 2001;Pliego, 2004) or supermoleculepolarizable continuum approach (Zhan et al, 2000;Xiong and Zhan, 2006). Recently, this combined supermoleculecontinuum approach was successfully applied to the basic hydrolysis of amides and esters (Haffner et al, 1999;Zhan et al, 2000Zhan et al, , 2007Pliego, 2004) in water and to the water exchange on aquated Al(III) species in aqueous solution (Qian et al, 2008a,b).…”

Section: Model Reactionsmentioning

confidence: 99%