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Biomedical subjects

H J Morowitz

Publications and source records attributed to H J Morowitz.

At least 145 records · Page 8Linked to original sources

Molecular mechanisms for proton transport in membranes.

Likely mechanisms for proton transport through biomembranes are explored. The fundamental structural element is assumed to be continuous chains of hydrogen bonds formed from the protein side groups, and a molecular example is presented. From studies in ice, such chains are predicted to have low impedance and can function as proton wires. In addition, conformational changes in the protein may be linked to the proton conduction. If this possibility is allowed, a simple proton pump can be described that can be reversed into a molecular motor driven by an electrochemical potential across the membrane.

Biological Transport, Active↗

Yellow is mellow.

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California↗

Psychosclerosis.

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Humans↗

Dull realities.

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Fear↗

Deep purple.

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Adenosine Triphosphate↗

Proton semiconductors and energy transduction in biological systems.

Energy transduction processes in biology are analyzed in terms of ordered chains of hydrogen bonds. The theory is an extension of studies on proton conductance in ice and is stimulated by current ideas on the role of hydrogen ions in oxidative phosphorylation and photophosphorylation. The possibility of a protochemistry paralleling electrochemistry is presented along with experimental evidence. The theory relating transmembrane electrochemical potential difference of hydrogen ion concentration to the synthesis of ATP is reviewed. The thermodynamics of hydrogen transfer across a membrane is treated including electrochemical and electromechanical factors. As a prelude to considering ATP synthesis, the acid-base dissociation reactions of ATP, ADP, and phosphate are analyzed. The thermodynamics of ATP synthesis is discussed and a detailed model is presented coupling the synthesis to proton transport. The model assumes a gated proton semiconductor that carries protons and allows them to interact specifically with well-defined substrate molecules. The physics of proton transport is outlined and various methods examined in the context of biological membranes. Emphasis is placed on solid-state proton semiconductors and the present theory of such structures is given. A section is included on possible biological applications of these semiconductors.

Adenosine Diphosphate↗

Hydration of phosphatidylocholine. Adsorption isotherm and proton nuclear magnetic resonance studies.

Adsorption-desorption isotherms were obtained for water binding by 1,2-dimyristoylphosphatidylcholine in the temperature range 15 degrees-35 degrees C. The isotherms were analyzed by Brunauer et al.'s (BET) theory and also a polarization theory, the latter being more successful in fitting the data. There was some evidence for a change in the surface field of the lipid bilayer around 25 degrees C. Proton T1 and T2 measurements were used to obtain a log-normal molecular correlation time distribution for water protons in these systems. This distribution was compared with the isotherm data to effect a description of several classes of water molecules.

Magnetic Resonance Spectroscopy↗