Reiss U, Rothstein M
J Biol Chem. 1975 Feb 10;250(3):826-30.
Isocitrate lyase from both young and old free living nematodes (Turbatrix aceti) has been purified and compared. The "old" enzyme consists of the same five isozymes as the "young" preparation, but with quantitative differences. The enzyme shows an age-related decline in specific activity. Use of antibodies has confirmed the accumulation of cross-reacting material in old organisms as found by Gershon and Gershon ((1970) Nature 227, 1214), using crude homogenates. Km, molecular weight, subunit size, and behavior toward the inhibitors oxalate, malonate, and tartronate all appear unchanged. Although the enzyme isolated from old organisms has a sharply reduced specific activity, it binds as well to an affinity column as does "young" enzyme. It is tentatively concluded that the loss of specific activity in the "old" enzyme is due to the presence of partially active molecules, rather than to a mixture of active and inactive molecules.
已对来自自由生活的年轻和老龄醋线虫（Turbatrix aceti）的异柠檬酸裂解酶进行了纯化和比较。“老龄”酶与“年轻”制剂一样，由相同的五种同工酶组成，但存在数量差异。该酶的比活性呈现与年龄相关的下降。正如格申和格申（(1970)《自然》227, 1214）使用粗匀浆所发现的那样，抗体的使用证实了老龄生物体中交叉反应物质的积累。米氏常数、分子量、亚基大小以及对抑制剂草酸盐、丙二酸盐和酒石酸盐的反应均未发生变化。尽管从老龄生物体中分离出的酶比活性大幅降低，但它与“年轻”酶一样能很好地结合到亲和柱上。初步得出结论，“老龄”酶比活性的丧失是由于存在部分活性分子，而非活性分子与非活性分子的混合物。
