Paliyath G, Poovaiah B W
Department of Horticulture and Landscape Architecture, Washington State University, Pullman 99164-6414, USA.
Plant Cell Physiol. 1985;26(1):201-9.
While studying the calmodulin activity in post-climacteric apples, a heat stable, dialyzable component that inhibited calmodulin-promoted phosphodiesterase activity was detected. The compound(s) that inhibited calmodulin activity did not bind to Dowex-50, H+ or Dowex-2, Cl- and was exclusively present in the neutral fraction. The inhibitors irreversibly bound to polyvinylpolypyrrolidone indicating their phenolic nature. Fractionation of the neutral fraction on a C18-microbondapak column and analysis for the inhibition of calmodulin-promoted phosphodiesterase activity showed significant inhibitory activity associated with fractions eluted 5 min, 15 min and 18 min after injection. Perdeuteriomethylation and combined gas chromatographic-mass spectrometric analysis of the inhibitors showed them to be flavonoids. (+)-Catechin was identified in the fraction eluted 5 min after injection that also showed maximum inhibition. Other flavonoids such as epicatechin, quercetin and naringenin also inhibited calmodulin-promoted phosphodiesterase activity. Among the phenolic compounds commonly encountered in plant tissue only caffeic acid inhibited calmodulin-promoted phosphodiesterase activity. Inhibition by catechin and caffeic acid could be reversed by increasing the calmodulin concentration in the assay mixture. Both catechin and caffeic acid inhibited Ca- and calmodulin-promoted phosphorylation of soluble proteins from corn coleoptiles. The physiological properties of flavonoids are discussed in light of this evidence.
在研究更年后期苹果中的钙调蛋白活性时，检测到一种热稳定、可透析的成分，它能抑制钙调蛋白促进的磷酸二酯酶活性。抑制钙调蛋白活性的化合物不与Dowex - 50（H⁺型）或Dowex - 2（Cl⁻型）结合，且仅存在于中性组分中。这些抑制剂不可逆地结合到聚乙烯聚吡咯烷酮上，表明它们具有酚类性质。在C18 - 微键合硅胶柱上对中性组分进行分离，并分析其对钙调蛋白促进的磷酸二酯酶活性的抑制作用，结果显示，与进样后5分钟、15分钟和18分钟洗脱的组分相关的显著抑制活性。对抑制剂进行全氘代甲基化及气相色谱 - 质谱联用分析表明它们是黄酮类化合物。在进样后5分钟洗脱的组分中鉴定出（+） - 儿茶素，该组分也显示出最大抑制作用。其他黄酮类化合物如表儿茶素、槲皮素和柚皮苷也抑制钙调蛋白促进的磷酸二酯酶活性。在植物组织中常见的酚类化合物中，只有咖啡酸抑制钙调蛋白促进的磷酸二酯酶活性。通过增加测定混合物中钙调蛋白的浓度，可以逆转儿茶素和咖啡酸的抑制作用。儿茶素和咖啡酸都抑制钙和钙调蛋白促进的玉米胚芽鞘可溶性蛋白的磷酸化。根据这些证据对黄酮类化合物的生理特性进行了讨论。
