Frankel L K, Bricker T M
Department of Botany, Louisiana State University, USA.
FEBS Lett. 1989 Nov 6;257(2):279-82. doi: 10.1016/0014-5793(89)81552-2.
Using a combination of cyanogen bromide cleavage and endoproteinase digestion we have shown that the putative epitope for the monoclonal antibody FAC2 lies in the region 360Pro(-391)Ser on the apoprotein of CPa-1. This region lies entirely within the large extrinsic loop of this protein. We have shown previously that the epitope of FAC2 becomes exposed in oxygen-evolving membranes upon treatment with alkaline Tris which releases all four of the manganese associated with the oxygen-evolving site of photosystem II. The epitope is not exposed, however, after CaCl(2) treatment and exposure to low concentrations of chloride, conditions which lead to the release of two of the four manganeses associated with the oxygen-evolving site. These results suggest that, upon release of the chloride-insensitive manganese from photosystem II membranes, a conformational change occurs which leads to the exposure of 360Pro(-391)Ser on CPa-1 to the monoclonal antibody FAC2.
通过结合使用溴化氰裂解和内肽酶消化，我们已经证明单克隆抗体FAC2的推定表位位于CPa - 1载脂蛋白上的360Pro(-391)Ser区域。该区域完全位于该蛋白质的大外部环内。我们之前已经表明，在用碱性Tris处理后，FAC2的表位在放氧膜中暴露，碱性Tris会释放与光系统II放氧位点相关的所有四个锰。然而，在CaCl₂处理和暴露于低浓度氯化物后，表位并未暴露，这些条件会导致与放氧位点相关的四个锰中的两个被释放。这些结果表明，从光系统II膜中释放出对氯化物不敏感的锰后，会发生构象变化，从而导致CPa - 1上的360Pro(-391)Ser暴露于单克隆抗体FAC2。
