サイトカイニン類と受容体との相互作用機構 : 定量的構造活性相関によるアプローチ
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概要
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Many biologically active substances exert their activity as the result of a specific interaction with a cellular component, the receptor, that triggers off the sequence of biological events leading to the final response. Thus the mode of interaction of a bioactive compound with the receptor would be best understood by analysing its interaction with the isoloated receptor molecule.<BR>In case of plant hormones, binding protein(s) can be isolated but can not at present be identified as the real receptor. Indirectly, however, the quantitative structureactivity relationship can be used to probe the binding between a bio-active molecule and its receptor. This methodology assumes that the variation in biological activity of a series of compounds reflects differences in both the permeability of the environment to these compounds and their affinity to the active site. Thus the results of the analysis are thought to reflect the interaction profile in terms of physical and structural parameters if the permability factor is of little significance or considered separately. In this sense, the methodology has been applied to the analysis of cytokinins, a class of plant hormomes which consists of two series of compounds, N<SUP>6</SUP>-substituted adenines arid diphenylureas. The results for adenylate cytokinins indicated an optimum steric condition for activity in terms of the maximum width of the N<SUP>6</SUP>-substituent. The electron-withdrawing effect is thought to enhance the activity through both series. Position-specific steric and hydrophobic effects of substituents on the benzene ring of the diphenylureas were suggested to participate in the variation of activity. Based on inferences made from the analyses, a hypothetical map for the mode of interaction of these two sets of cytokinins at the site of action has been proposed.
- 日本生物物理学会の論文