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Start Over Topic conformational change
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1. Digestion of the basic trypsin inhibitor of bovine pancreas by thermolysin

Author

Beatrice Kassell and Tsun-Wen Wang

Subjects
Electrophoresis, Paper, Conformational change, Protein Denaturation, Hot Temperature, Chemical Phenomena, Trypsin inhibitor, Biophysics, Bacillus, Biochemistry, chemistry.chemical_compound, Aprotinin, Thermolysin, Endopeptidases, medicine, Trypsin, Molecular Biology, Chromatography, Kunitz STI protease inhibitor, Cell Biology, Chemistry, medicine.anatomical_structure, chemistry, Ninhydrin, Indicators and Reagents, Digestion, Pancreas
Abstract

Extensive digestion of the basic trypsin inhibitor by thermolysin at 60–80° has been demonstrated by loss of inhibitory activity, increase in ninhydrin positive material and separation of the breakdown products by electrophoresis. Formation of the inhibitor-trypsin complex does not protect the inhibitor from digestion by thermolysin; both components are digested. Between 40° and 80° the inhibitor undergoes a reversible transition involving a slight conformational change; this may account for its susceptibility to thermolysin.

Published
1970

2. Transport phenomena in a model membrane accompanying a conformational change: transient processes in response to external stimuli

Author

Tohru Yoshioka, Tohru Sugita, Mizuko Yoshida, and Naoki Kamo

Subjects
Membrane potential, Paper, Conformational change, Physiology, Stereochemistry, Chemistry, Hydrostatic pressure, Biophysics, Electric Conductivity, Biological Transport, Membranes, Artificial, Oleic Acids, Cell Biology, Critical value, Models, Biological, Electric Stimulation, Membrane Potentials, Membrane, Organophosphorus Compounds, Electrical resistance and conductance, Oscillometry, Transport phenomena, Voltage
Abstract

A model membrane composed of a filter paper and dioleylphosphate was studied by applying various kinds of external stimuli. When the concentration in the external solution was varied successively, the physico-chemical properties of the membrane changed drastically at a certain valueC t . The relationships between the electrical response and the external stimuli studied are as follows: (1) The membrane potential oscillates spontaneously in a spikelike fashion when the concentration of the external solution is suddenly changed. (2) The current through the membrane oscillates in spikelike fashion for a duration of about 50 msec when the constant external voltage, V larger than a certain value V c , is applied across the membrane. (3) The electric resistance sharply decreases, and a kind of action potential similar to that observed in living tissues is produced when a short rectangular electric stimulus, whose magnitude is higher than a critical value V p , is applied. (4) If a hydrostatic pressure difference across the membrane is applied with appropriate salt conditions, the value of the membrane potential varies with time, as in the case of (3). The observed changes in emf and electric resistance are discussed in connection with the conformational change of DOPH molecules in the membrane.

Published
1973

3. Fragmented E. coli methionine tRNA f as methyl acceptor for rat liver tRNA methylase: alteration of the site of methylation by the conformational change of tRNA structure resulting from fragmentation

Author

Yoshiyuki Kuchino, Takeshi Seno, and Susumu Nishimura

Subjects
Electrophoresis, Paper, Conformational change, S-Adenosylmethionine, Methyltransferase, Guanine, Chemical Phenomena, Formates, Polynucleotides, Biophysics, Biology, Biochemistry, Methylation, chemistry.chemical_compound, Methionine, Ribonucleases, RNA, Transfer, Transferases, Escherichia coli, Animals, Fragmentation (cell biology), Molecular Biology, Pancreas, Carbon Isotopes, Binding Sites, Nucleosides, Cell Biology, Methyltransferases, Alkaline Phosphatase, Chromatography, Ion Exchange, Acceptor, Nucleotidyltransferases, In vitro, Rats, Chemistry, RNA, Bacterial, chemistry, Liver, Transfer RNA
Abstract

In vitro methylation of E. coli tRNAfMet fragments or their reconstituted molecule by rat liver methylase showed that (1) the whole tRNA molecule was not necessary for recognition by tRNA methylase, and (2) the extent and the site of methylation of fragments differed depending upon the type of fragment used. This indicates that the conformational structure of the methyl acceptor molecule is important for recognition by the tRNA methylase.

Published
1971