Some quantitative relationships for ionization reactions at high pressures

El'yanov, BS; Hamann, S. D.

doi:10.1071/ch9750945

Cited by 48 publications

(32 citation statements)

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“…The dependence of K w (D 2 O) on pressure was estimated using eq 5. The constant b has been empirically determined to be 9.2 × 10 -5 bar -1 (25,27). …”

Section: Resultsmentioning

confidence: 99%

Local Stability and Dynamics of Apocytochrome b₅₆₂ Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure^,

1998

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Hydrostatic pressure is used to perturb the manifold of states available to apocytochrome b562 and to examine the energetics and dynamics of the protein using hydrogen exchange monitored in real-time by heteronuclear spectroscopy at pressures ranging up to 1. 1 kbar. An analytical framework for interpreting the effects of hydrostatic pressure on the physical events leading to protein hydrogen exchange is presented. The protein is found to have three regions of subglobal cooperative stability. The most stable region, or core, is composed of the central two helices of the bundle. The dependence of the global unfolding free energy upon pressure is first order and associated with a negative volume change of -102 mL mol-1. Two additional regions of cooperative structure are identified, and both also have negative volume changes associated with their unfolding at high pressure. Surprisingly, one of the subglobal unfolding units shows a significant positive volume change at low pressures (<200 bar) suggesting the presence of a highly mispacked open state at ambient pressure. The three regions of cooperative stability are the same as identified by perturbation with chemical denaturant. The implications of these results for issues in protein folding and the form of the energy landscape of globular proteins are discussed.

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“…The dependence of K w (D 2 O) on pressure was estimated using eq 5. The constant b has been empirically determined to be 9.2 × 10 -5 bar -1 (25,27). …”

Section: Resultsmentioning

confidence: 99%

Local Stability and Dynamics of Apocytochrome b₅₆₂ Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure^,

1998

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“…The extent of the pH-shift can be theoretically predicted if values for the empirical constants involved in Eq. 1 are available (Neuman et al 1973;El'Yanov and Hamann 1975):…”

Section: Effects Of High-pressure Processing On Food Systemsmentioning

confidence: 99%

High-Pressure Processing Technologies for the Pasteurization and Sterilization of Foods

Mújica-Paz

Valdez-Fragoso

Samson

et al. 2011

Food Bioprocess Technol

292

114

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The food-processing industry has made large investments in processing facilities relying mostly on conventional thermal processing technologies with well-established reliability and efficacy. Replacing them with one of the novel alternatives recently developed is a decision that must be carefully approached. Among them, high-pressure processing (HPP), at room or refrigerated temperature, is now a wellestablished option experiencing worldwide commercial growth. Surveys have shown an excellent consumer acceptance of HPP technology. For financial feasibility reasons, HPP treatments must be kept short, a challenge that can be met by some of the alternatives here reviewed such as the use of the hurdle technology concept. Although HPP technology is limited to pasteurization treatments, the combination of high pressure and high temperature used in pressureassisted thermal processing (PATP) can be used to sterilize foods. An analysis of alternatives to achieve the inactivation of bacterial spores at the lowest temperature possible highlights the need for additional research on the use of germinants. Because of incomplete research, PATP presents several implementation challenges, including the modeling of food temperature, the determination of inactivation kinetics particularly for bacterial spores, and the prediction of chemical changes including the potential formation of toxic compounds.

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“…The vast domain of processed foods, and the huge number of chemical reactions taking place in different food matrices, poses food scientists and engineers with the challenges of identifying, characterizing and modeling at least the most significant chemical reactions under these novel processing conditions. A further challenge is that the experimental work on chemical changes under high pressure, and the development of predictions to real foods, must consider also the temporary, media-and pressure-dependent pH shift which can be estimated using the following empirical equation [16]:…”

Section: A Reaction Kinetics Approach To Understand Chemical Changes mentioning

confidence: 99%

Reaction Kinetics Analysis of Chemical Changes in Pressure-Assisted Thermal Processing

et al. 2009

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Pressure-assisted thermal processing (PATP) at T \ 100°C can be used when enzyme inactivation and pasteurization by high pressure processing (HPP) is not feasible due to long processing times while PATP at T [ 100°C can be used when bacterial spores inactivation is necessary. In PATP, the adiabatic compression/decompression heat increases/decreases temperature almost instantaneously, and the simultaneous application of high pressure (*600-700 MPa) and temperature (*100-120°C) accelerates spore inactivation. PATP effects on chemical changes are analyzed using a reaction kinetics approach including activation volume (V a ) and activation energy (E a ) values. Reaction rates increase or decrease with pressure for negative or positive V a values, respectively, while rate temperature and pressure sensitivity depends on the magnitude of E a and V a values, respectively. The complex effects of food matrix, pH, dissolved oxygen, and presence of antioxidants show that optimization of vitamin, pigment and flavor retention while ensuring PATP microbial and enzyme inactivation will require substantially more chemical reaction kinetics research.

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Some quantitative relationships for ionization reactions at high pressures

Cited by 48 publications

References 0 publications

Local Stability and Dynamics of Apocytochrome b₅₆₂ Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure^,

Local Stability and Dynamics of Apocytochrome b₅₆₂ Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure^,

High-Pressure Processing Technologies for the Pasteurization and Sterilization of Foods

Reaction Kinetics Analysis of Chemical Changes in Pressure-Assisted Thermal Processing

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Some quantitative relationships for ionization reactions at high pressures

Cited by 48 publications

References 0 publications

Local Stability and Dynamics of Apocytochrome b562 Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure,

Local Stability and Dynamics of Apocytochrome b562 Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure,

High-Pressure Processing Technologies for the Pasteurization and Sterilization of Foods

Reaction Kinetics Analysis of Chemical Changes in Pressure-Assisted Thermal Processing

Contact Info

Product

Resources

About

Local Stability and Dynamics of Apocytochrome b₅₆₂ Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure^,

Local Stability and Dynamics of Apocytochrome b₅₆₂ Examined by the Dependence of Hydrogen Exchange on Hydrostatic Pressure^,