ANTIBACTERIAL CHARACTERISTICS OF FISH PROTAMINES. VIII1 EFFECT OF CLUPEINE SULFATE ON THE MEMBRANE- ATPase ACTIVITY AND MEMBRANE STRUCTURE OF BACILLUS SUBTILIS

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We studied the effect of clupeine sulfate on a vital membrane-bound enzyme (adenosinetriphosphatase or ATPase). Clupeine stimulated the Mg²⁺-ATPase activity to 250% of the control level but the stimulatory effect diminished with more than 200μg of clupeine/ml. Considering the vital metabolic functions of this enzyme it appears that the stimulatory effect of clupeine on this enzyme may contribute to the destruction of membrane function. Phosphatidylethanolamine, a typical membrane phospholipid inactivated and blocked the stimulatory effect of clupeine on the ATPase activity.
In view of the strong interaction between clupeine and membrane lipids, the effect of clupeine on the membrane structure of Bacillus subtilis was studied by incorporating a hydrophobic fluorescent dye (1, 6-diphenyl- 1, 3, 5-hexatriene) molecule in the isolated cell membranes. Clupeine increased the fluorescence intensity and decreased the fluorescence polarization of the membrane dye environment. This indicated a structural change in the cell membrane.