Department of Life Sciences, Indiana State University, Terre Haute, Indiana 47809.
Plant Physiol. 1992 Feb;98(2):472-9. doi: 10.1104/pp.98.2.472.
Polyphenoloxidase was purified from chloroplasts of broad bean leaves (Vicia faba L.) to apparent homogeneity. The enzyme was composed of two proteins with an apparent mass of 65 and 68 kilodaltons after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isolated enzyme contained covalently attached carbohydrates and bound concanavalin A, Phaseolus vulgaris erythroagglutinin, and Ricinus communis agglutinin lectins. Under native isoelectric focusing, several charged isoforms were present in the pH range of 4 to 6. Many, if not all, of the isoforms separated by isoelectric focusing were glycosylated and bound concanavalin A. All these isoforms shared a 65 kilodalton protein in common, and some of the isoforms were associated with both a 65 and 68 kilodalton protein. Isoforms separated by isoelectric focusing in the presence of 9 molar urea followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a similar pattern of proteins within a slightly higher pH range from 5 to 6.5.
多酚氧化酶从蚕豆叶片(Vicia faba L.)的叶绿体中被纯化到明显的均一性。该酶由两种蛋白质组成,在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳后,其表观分子量分别为 65 和 68 千道尔顿。分离出的酶含有共价结合的碳水化合物和结合的刀豆球蛋白 A、菜豆红细胞凝集素和蓖麻凝集素。在天然等电聚焦下,在 pH 值为 4 到 6 的范围内存在几种带电荷的同工型。如果不是所有的同工型,那么通过等电聚焦分离的许多同工型都被糖基化并与刀豆球蛋白 A 结合。所有这些同工型都共有一个 65 千道尔顿的蛋白质,而有些同工型与 65 和 68 千道尔顿的蛋白质都有关联。在存在 9 摩尔尿素的情况下通过等电聚焦分离的同工型,随后进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳,显示出在稍微较高的 pH 值范围(5 到 6.5)内具有相似的蛋白质模式。