Concentration Threshold and Amplification Exhibited by a Helicene Oligomer during Helix‐Dimer Formation: A Proposal on How a Cell Senses Concentration Changes of a Chemical |
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| Authors: | Yo Kushida Dr. Masanori Shigeno Prof. Dr. Masahiko Yamaguchi |
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| Affiliation: | Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai, 980‐8578 (Japan) |
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| Abstract: | Sulfonamidohelicene tetramer (M)‐ 1 exhibits a concentration threshold and amplification phenomena in solution during helix‐dimer formation from a random‐coil. The (M)‐tetramer is a random‐coil below a threshold concentration, and the concentration of the helix‐dimer is irreversibly amplified once the threshold concentration is exceeded. For example, a 15 % increase in (M)‐tetramer total concentration from 0.6 to 0.7 mM induces an 8‐fold increase in the concentration of the helix‐dimer, being 8:0.15=53‐fold amplification, under temperature oscillation conditions between 47 and 49 °C. Experiments without oscillation also exhibit concentration amplification. The threshold and amplification phenomenon involves concentration hysteresis, being away from equilibrium, and self‐catalysis. On the basis of this study, a proposal on how a biological cell senses concentration changes of a chemical substance is provided. |
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| Keywords: | concentration amplification concentration hysteresis helical structures self‐catalysis sulfonamides |
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