Edwardsiella tarda外毒素之磷脂?活性

Abstract

經75% ammonium sulfate沉澱，初步純化的Edwardsiella tarda之外毒素，會引起人類紅血球的溶血。將此外毒素通入G-25 Sephadex Column去除鹽類，可分出5個蛋白質群(G25-1?5)。其中G25-1含有可以水解phosphotidylcholine (PC)和sphingo-myelin (SM)之磷脂?C；G25-2則含有會水解PC、SM和phos-photidylethanolamide 2(PE)之磷脂?。將G25-2再通入DEAE-Sephacel Anion Exchange Column可得6個蛋白質群(DEAE1?6)。其中DEAE2含有對PE具種別性之磷脂?A，DEAE5能水解PC和SM，DEAE6則含有對PE具種別性之磷脂?C。DEAE5進一步以Electrofocusing Column分離，可得5個蛋白質群(E1?5)。E3、E5分別含有對PC具種別性之磷脂?A、C。此乃首次發現E.tarda之外毒素具磷脂?的活性。

The crude exotoxin of Edwardsiella tarda, obtained by 75% ammonium sulfate precipitation , caused hemolysis of human erythrocytes. The exotoxin was then desalted by G-25 Sephadex Column and recovered five peaks. Two major peaks (G25-1,2) had lipase activities. G25-1 Contains phospholipase C which hydrolyzed phosphotidylcholine (PC) and sphingomyelin (SM). G25-2 hydrolyzed PC, SM and phosphotidyleth-anolamide(PE). G25-2 was then fractionated by DEAE-Sephacel column chromatography. Three different fractions showed various phospholipase activities. DEAE 2 contained basic PE- specific phospholipase A. DEAE 5 hydrolyzed sphingomyelin and PC; DEAE 6 contained acidic phospholipase C which hydrolyzed PE . DEAE5 was further seperated by Electrofocusing Column . Two fractions recovered lipase activities. E3 contained PC-specific phospholipase A; while E5 had PC-specific phospholipase C . This shows that the exotoxin of E.tarda had various kinds of phospholipaseactivities.