Sander A, Krausgrill S, Greiner S, Weil M, Rausch T
Botanisches Institut, Ruprecht-Karls-Universität, Heidelberg, Germany.
FEBS Lett. 1996 May 6;385(3):171-5. doi: 10.1016/0014-5793(96)00378-x.
Vacuolar (VI) and cell wall invertases (CWI) of higher plants can be inactivated in vitro and, possibly, in vivo by proteinaceous inhibitors. The respective mechanisms have not yet been compared. Therefore, partially purified CWI from transformed tobacco cells and VI from tomato fruit were preincubated with invertase-inhibitor fractions isolated from the same tissues. Both inhibitors were able to inhibit both invertases. However, VI was fully inhibited within less than 1 min by both inhibitors, whereas inactivation of CWI was much slower. Furthermore, CWI, but not VI, was strongly protected against inhibition by sucrose. A polyclonal antiserum directed against the tobacco inhibitor (I(NT)) cross-reacted with a 19 kDa polypeptide in the partially purified tomato inhibitor (I(LE)) fraction. The results indicate that I(NT) and I(LE)have similar structural properties, whereas the mechanism of inactivation is clearly different for CWI and VI.
高等植物的液泡转化酶（VI）和细胞壁转化酶（CWI）在体外甚至可能在体内会被蛋白质类抑制剂灭活。尚未对各自的作用机制进行比较。因此，将从转基因烟草细胞中部分纯化得到的CWI和从番茄果实中提取的VI与从相同组织中分离得到的转化酶抑制剂组分进行预孵育。两种抑制剂都能够抑制这两种转化酶。然而，两种抑制剂在不到1分钟的时间内就能完全抑制VI，而CWI的失活则要慢得多。此外，蔗糖能强烈保护CWI免受抑制，但对VI却没有这种作用。一种针对烟草抑制剂（I(NT)）的多克隆抗血清与部分纯化的番茄抑制剂（I(LE)）组分中的一种19 kDa多肽发生交叉反应。结果表明，I(NT)和I(LE)具有相似的结构特性，而CWI和VI的失活机制明显不同。
