Abstract

P56, a cytotoxin with a molecular weight of 56 kDa and an isoelectric point of 6.2 was isolated and purified from the cell-free supernatant of Salmonella choleraesuis CH12440 culture. P56 was a secretory protein. It could be detected as early as 3 hr in the supernatant of bacterial culture, and the presence of calcium in the medium would increase the secretion by a factor of 3.2. P56 had dose-dependent effects on mouse macrophage cell line P388-D1 and mouse peritoneal macrophages: It caused death of both kinds of cells at high concentrations. In contrast, it had a mitogenic effect on the cells at lower doses. Western blot analysis showed that the antibody raised against P56 reacted to P56 and proteins of S. choleraesuis lysate. However, there was no cross-reaction between P56 and the antibody raised against the dead cells.

中文摘要

P56 是一種由霍亂沙氏桿菌CH12440 之培養基上清液分離到的細胞毒素。它的分子 量56 千道爾頓，等焦點6.2，是一種分泌型的蛋白質。在細菌培養3 小時即可於上清液中偵測到它的存在，而且在培養基中有鈣離子時，其存在量為沒有鈣離子存在時的3.2倍。P56 對老鼠巨噬細胞株P388-D1 及腹膜巨噬細胞的影響視其計量而定：在高濃度下，它會引起這兩種細胞的死亡；在低濃度下，它反而會促進細胞的分裂。在西方轉漬分析中，P56 的抗體可與P56 蛋白質本身及沙氏桿菌的細胞溶解物反應，但是P56 與利用死菌製備的抗體沒有交叉反應產生。

Keyword: Salmonella choleraesuis, Secretory cytotoxin, Cytotoxic effect, Mitogenic effect