Fernández-Maculet J C, Yang S F
Mann Laboratory, Department of Vegetable Crops, University of California, Davis, California 95616.
Plant Physiol. 1992 Jun;99(2):751-4. doi: 10.1104/pp.99.2.751.
Ethylene-forming enzyme (EFE) was isolated from apple (Malus domestica Borkh. cv Golden Delicious) fruit tissue. The enzyme activity in the homogenate is associated with the pellet fraction and can be solubilized with Triton X-100 or polyvinylpolypyrrolidone. The solubilized enzyme system resembles the in vivo system in that it exhibits a low K(m) (17 micromolar) for its substrate 1-aminocyclopropane-1-carboxylic acid (ACC), is stereospecific toward 2-ethyl-ACC stereoisomers for 1-butene production, and is inhibited by cobalt ions and alpha-aminoisobutyric acid. Intact preclimacteric fruits treated with exogenous ethylene showed a marked increase in in vivo EFE activity and this increase was accompanied by a parallel increase in in vitro EFE activity. These results support the notion that the isolated EFE represents the authentic in vivo activity.
乙烯形成酶(EFE)是从苹果(Malus domestica Borkh. cv金冠)果实组织中分离出来的。匀浆中的酶活性与沉淀部分相关,并且可以用 Triton X-100 或聚乙烯聚吡咯烷酮溶解。溶解的酶系统类似于体内系统,因为它对其底物 1-氨基环丙烷-1-羧酸(ACC)表现出低 Km(17 微摩尔),对用于产生 1-丁烯的 2-乙基-ACC 立体异构体具有立体特异性,并且受到钴离子和α-氨基异丁酸的抑制。用外源乙烯处理的未成熟跃变前果实显示体内 EFE 活性显著增加,并且这种增加伴随着体外 EFE 活性的平行增加。这些结果支持了分离出的 EFE 代表真实体内活性的观点。