Kinetic behavior of enzymes in artificial membranes. Inhibition and reversibility effects

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

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MODELS OF THE THERMODYNAMIC AND KINETIC BEHAVIOR OF FUEL CELLS AND THEIR USE IN THE RATIONAL DESIGN OF FUEL CELL ELECTRODES

Annual Reviews of Heat Transfer ◽

10.1615/annualrevheattransfer.v14.290 ◽

2005 ◽

Vol 14 (14) ◽

pp. 529-576

Author(s):

Ernest G. Cravalho ◽

Fritz Pierre, Jr.

Keyword(s):

Fuel Cells ◽

Fuel Cell ◽

Rational Design ◽

Kinetic Behavior ◽

Fuel Cell Electrodes

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Faculty Opinions recommendation of Single molecule analysis of RNA polymerase elongation reveals uniform kinetic behavior.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1009694.139508 ◽

2002 ◽

Author(s):

Daniel Reines

Keyword(s):

Rna Polymerase ◽

Single Molecule ◽

Kinetic Behavior ◽

Single Molecule Analysis

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Omp35, a New Enterobacter aerogenes Porin Involved in Selective Susceptibility to Cephalosporins

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.6.2153-2158.2004 ◽

2004 ◽

Vol 48 (6) ◽

pp. 2153-2158 ◽

Cited By ~ 25

Author(s):

Charléric Bornet ◽

Nathalie Saint ◽

Lilia Fetnaci ◽

Myrielle Dupont ◽

Anne Davin-Régli ◽

...

Keyword(s):

Membrane Permeability ◽

Outer Membrane ◽

Antibiotic Susceptibility ◽

Enterobacter Aerogenes ◽

Artificial Membranes ◽

Specific Location ◽

Outer Membrane Permeability ◽

Constriction Region ◽

High Conductance

ABSTRACT In Enterobacter aerogenes, β-lactam resistance often involves a decrease in outer membrane permeability induced by modifications of porin synthesis. In ATCC 15038 strain, we observed a different pattern of porin production associated with a variable antibiotic susceptibility. We purified Omp35, which is expressed under conditions of low osmolality and analyzed its pore-forming properties in artificial membranes. This porin was found to be an OmpF-like protein with high conductance values. It showed a noticeably higher conductance compared to Omp36 and a specific location of WNYT residues in the L3 loop. The importance of the constriction region in the porin function suggests that this organization is involved in the level of susceptibility to negative large cephalosporins such as ceftriaxone by bacteria producing the Omp35 porin subfamily.

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