Alpi A, Beevers H
Thimann Laboratories, University of California, Santa Cruz, California 95064.
Plant Physiol. 1981 Mar;67(3):499-502. doi: 10.1104/pp.67.3.499.
The stability of catalase, fumarase, and isocitrate lyase from deliberately broken organelles in crude extracts from endosperm tissue of castor bean seedlings has been examined. These enzymes are relatively stable at 2 C in extracts from endosperm of 2-day seedlings, but rapid losses of activity occur in extracts from older seedlings. These losses are shown to be brought about by the thiol-proteinase present in the extracts. The inclusion of 35% glycerol prevented the loss of catalase, fumarase, and isocitrate lysase activity, and various inhibitors of proteinases afforded limited protection. The most striking protectant was leupeptin, an inhibitor of serine and thiol-proteinases. Leupeptin completely inhibited the loss of activity of the three enzymes in crude extracts and improved yields when included in the grinding medium.
对蓖麻籽幼苗胚乳组织粗提物中故意破碎的细胞器中的过氧化氢酶、延胡索酸酶和异柠檬酸裂解酶的稳定性进行了研究。这些酶在2日龄幼苗胚乳提取物中于2℃时相对稳定，但在较老幼苗的提取物中活性迅速丧失。结果表明，这些活性丧失是由提取物中存在的巯基蛋白酶引起的。加入35%的甘油可防止过氧化氢酶、延胡索酸酶和异柠檬酸裂解酶活性的丧失，各种蛋白酶抑制剂提供了有限的保护。最显著的保护剂是亮抑酶肽，一种丝氨酸和巯基蛋白酶的抑制剂。亮抑酶肽完全抑制了粗提物中三种酶活性的丧失，并且当包含在研磨介质中时提高了产量。
