U.S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, Louisiana.
Plant Physiol. 1991 May;96(1):26-31. doi: 10.1104/pp.96.1.26.
Polyphenol oxidase (PPO) appears to be ubiquitous in higher plants but, as yet, no function has been ascribed to it. Herein, we report on the localization of PPO based upon biochemical fractionation of chloroplast membranes in Vicia faba (broad bean) into various complexes and immunocytochemical electron microscopic investigations. Sucrose density gradient fractionations of thylakoid membranes after detergent solubilization reveals that PPO protein (by reactivity with anti-PPO antibody) and activity (based upon ability to oxidize di-dihydroxyphenylalanine) are found only in fractions enriched in photosystem II (PSII). Furthermore, of the PSII particles isolated using three different protocols utilizing several plant species, all had PPO. Immunogold localization of PPO on thin sections reveals exclusive thylakoid labeling with a distribution pattern consistent with other PSII proteins (80% grana, 20% stroma). These data strongly indicate that PPO is at least peripherally associated with the PSII complex.
多酚氧化酶（PPO）似乎普遍存在于高等植物中，但目前还没有赋予它任何功能。在此，我们根据蚕豆（Vicia faba）叶绿体膜的生化分级分离为各种复合物，并通过免疫细胞化学电子显微镜研究，报告了 PPO 的定位。去污剂溶解后，类囊体膜的蔗糖密度梯度分级分离表明，PPO 蛋白（通过与抗 PPO 抗体的反应）和活性（基于氧化二二羟苯丙氨酸的能力）仅存在于富含光系统 II（PSII）的级分中。此外，使用三种不同方案从几种植物中分离的 PSII 颗粒都含有 PPO。PPO 在薄切片上的免疫金定位显示，只有类囊体被标记，其分布模式与其他 PSII 蛋白一致（80%的基质，20%的基质）。这些数据强烈表明，PPO 至少与 PSII 复合物有外周关联。
