Botany Department, Washington State University, Pullman, Washington 99164-4230.
Plant Physiol. 1987 Sep;85(1):294-8. doi: 10.1104/pp.85.1.294.
Intact mesophyll and bundle sheath chloroplasts wee isolated from the NADP-malic enzyme type C(4) plants maize, sorghum (monocots), and Flaveria trinervia (dicot) using enzymic digestion and mechanical isolation techniques. Bundle sheath chloroplasts of this C(4) subgroup tend to be agranal and were previously reported to be deficient in photosystem II activity. However, following injection of intact bundle sheath chloroplasts into hypotonic medium, thylakoids had high Hill reaction activity, similar to that of mesophyll chloroplasts with the Hill oxidants dichlorophenolindophenol, p-benzoquinone, and ferricyanide (approximately 200 to 300 micromoles O(2) evolved per mg chlorophyll per hour). In comparison to that of mesophyll chloroplasts, the Hill reaction activity of bundle sheath chloroplasts of maize and sorghum was labile and lost activity during assay. Bundle sheath chloroplasts of maize also exhibited some capacity for 3-phosphoglycerate dependent O(2) evolution (29 to 58 micromoles O(2) evolved per milligram chlorophyll per hour). Both the mesophyll and bundle sheath chloroplasts were equally effective in light dependent scavenging of hydrogen peroxide. The results suggest that both chloroplast types have noncyclic electron transport and the enzymology to reduce hydrogen peroxide to water. The activities of ascorbate peroxidase from these chloroplast types was consistent with their capacity to scavenge hydrogen peroxide.
使用酶消化和机械分离技术，从 NADP-苹果酸酶类型 C(4)植物玉米、高粱（单子叶植物）和三齿滨藜（双子叶植物）中分离出完整的叶肉和束鞘叶绿体。该 C(4)亚组的束鞘叶绿体往往是无颗粒的，并且先前报道其缺乏光系统 II 活性。然而，将完整的束鞘叶绿体注入低渗介质后，类囊体具有高的希尔反应活性，类似于叶肉叶绿体的希尔氧化剂二氯酚靛酚、对苯醌和铁氰化物（每毫克叶绿素每小时约 200 到 300 微摩尔 O(2)产生）。与叶肉叶绿体相比，玉米和高粱束鞘叶绿体的希尔反应活性不稳定，在测定过程中会失去活性。玉米束鞘叶绿体还表现出一定的 3-磷酸甘油酸依赖性 O(2)产生能力（每毫克叶绿素每小时产生 29 到 58 微摩尔 O(2)）。叶肉和束鞘叶绿体在光依赖性清除过氧化氢方面同样有效。结果表明，这两种叶绿体类型都具有非循环电子传递和将过氧化氢还原为水的酶学特性。这些叶绿体类型的抗坏血酸过氧化物酶的活性与其清除过氧化氢的能力一致。
