Huang A H, Beevers H
J Cell Biol. 1973 Aug;58(2):379-89. doi: 10.1083/jcb.58.2.379.
Microbodies from rat liver and a variety of plant tissues were osmotically shocked and subsequently centrifuged at 40,000 g for 30 min to yield supernatant and pellet fractions. From rat liver microbodies, all of the uricase activity but little glycolate oxidase or catalase activity were recovered in the pellet, which probably contained the crystalline cores as many other reports had shown. All the measured enzymes in spinach leaf microbodies were solubilized. With microbodies from potato tuber, further sucrose gradient centrifugation of the pellet yielded a fraction at density 1.28 g/cm(3) which, presumably representing the crystalline cores, contained 7% of the total catalase activity but no uricase or glycolate oxidase activity. Using microbodies from castor bean endosperm (glyoxysomes), 50-60% of the malate dehydrogenase, fatty acyl CoA dehydrogenase, and crotonase and 90% of the malate synthetase and citrate synthetase were recovered in the pellet, which also contained 96% of the radioactivity when lecithin in the glyoxysomal membrane had been labeled by previous treatment of the tissue with [(14)C]choline. When the labeled pellet was centrifuged to equilibrium on a sucrose gradient, all the radioactivity, protein, and enzyme activities were recovered together at peak density 1.21-1.22 g/cm(3), whereas the original glyoxysomes appeared at density 1.24 g/cm(3). Electron microscopy showed that the fraction at 1.21-1.22 g/cm(3) was comprised of intact glyoxysomal membranes. All of the membrane-bound enzymes were stripped off with 0.15 M KCl, leaving the "ghosts" still intact as revealed by electron microscopy and sucrose gradient centrifugation. It is concluded that the crystalline cores of plant microbodies contain no uricase and are not particularly enriched with catalase. Some of the enzymes in glyoxysomes are associated with the membranes and this probably has functional significance.
对来自大鼠肝脏和多种植物组织的微体进行渗透压休克处理，随后以40,000 g离心30分钟，以获得上清液和沉淀部分。从大鼠肝脏微体中，沉淀中回收了所有的尿酸酶活性，但乙醇酸氧化酶或过氧化氢酶活性很少，正如许多其他报告所示，沉淀中可能含有晶核。菠菜叶微体中所有测定的酶都可溶解。对于来自马铃薯块茎的微体，对沉淀进一步进行蔗糖梯度离心，得到密度为1.28 g/cm³的部分，推测这代表晶核，其含有总过氧化氢酶活性的7%，但没有尿酸酶或乙醇酸氧化酶活性。使用来自蓖麻籽胚乳（乙醛酸循环体）的微体，沉淀中回收了50 - 60%的苹果酸脱氢酶、脂肪酰辅酶A脱氢酶和巴豆酸酶，以及90%的苹果酸合成酶和柠檬酸合成酶，当用[(14)C]胆碱预先处理组织使乙醛酸循环体膜中的卵磷脂被标记时，沉淀中还含有96%的放射性。当将标记的沉淀在蔗糖梯度上离心至平衡时，所有的放射性、蛋白质和酶活性都在峰值密度1.21 - 1.22 g/cm³处一起回收，而原始的乙醛酸循环体出现在密度1.24 g/cm³处。电子显微镜显示，密度为1.21 - 1.22 g/cm³的部分由完整的乙醛酸循环体膜组成。所有膜结合酶都能用0.15 M KCl去除，电子显微镜和蔗糖梯度离心显示“空壳”仍然完整。得出的结论是，植物微体的晶核不含尿酸酶，也没有特别富集过氧化氢酶。乙醛酸循环体中的一些酶与膜相关，这可能具有功能意义。
