Kowalski S P, Eannetta N T, Hirzel A T, Steffens J C
Department of Plant Breeding and Biometry, 252 Emerson Hall, Cornell University, Ithaca, New York 14853.
Plant Physiol. 1992 Oct;100(2):677-84. doi: 10.1104/pp.100.2.677.
Type A glandular trichomes of the wild potato (Solanum berthaultii Hawkes) entrap insects by rapidly polymerizing the trichome contents after breakage by insect contact. Polymerization of trichome exudate appears to be driven by a soluble polyphenol oxidase (PPO). PPO constitutes up to 70% of the protein in individually collected trichomes and reaches a concentration approaching 200 mum in these organs. Trichome PPO has been purified and shown to be a monomeric copper metalloprotein with an isoelectric point of 5.5, possessing only o-diphenol oxygen oxido-reductase activity, and is larger than most other reported PPOs, with relative molecular weight of 59,000. Chlorogenic and caffeic acid were the most readily oxidized of 14 phenolic substrates tested. Polyclonal antibodies raised against the relative molecular weight 59,000 S. berthaultii trichome PPO were used to show that S. tuberosum L. trichomes express low levels of a cross-reactive protein that lacks detectable PPO activity.
野生马铃薯（Solanum berthaultii Hawkes）的A型腺毛在被昆虫接触折断后，通过使毛状体内容物快速聚合来捕获昆虫。毛状体分泌物的聚合似乎是由一种可溶性多酚氧化酶（PPO）驱动的。在单独收集的毛状体中，PPO占蛋白质的比例高达70%，在这些器官中的浓度接近200微摩尔。毛状体PPO已被纯化，显示为一种单体铜金属蛋白，等电点为5.5，仅具有邻二酚氧氧化还原酶活性，且比大多数其他已报道的PPO更大，相对分子质量为59,000。在测试的14种酚类底物中，绿原酸和咖啡酸最容易被氧化。针对相对分子质量为59,000的伯氏茄毛状体PPO产生的多克隆抗体被用于表明马铃薯（Solanum tuberosum L.）毛状体表达低水平的一种缺乏可检测PPO活性的交叉反应蛋白。
