利用原子力顯微鏡觀測並分析紫色細胞膜的表面物性

Abstract

紫色細胞膜(PM)是由 細菌視紫紅質 (BR)和許多種類的脂質所組成的二維結構，受到光照後能單一方向將質子從胞內傳遞至胞外，形成膜內外質子濃度梯度，而能產生光電流。胞內(CP surface)與胞外(EC surface)因結構上的不同，所表現出來的特性也不同。我們利用原子力顯微鏡觀測到以不同的biotin對PM的兩面作選擇性的修飾，可較有效率的讓PM利用biotin-avidin鍵結吸附於基底。而分別對CP surface與EC surface作Force-distance Curve分析，發現EC surface其黏著力略大於CP surface，並且發現PM的黏著力也會隨著鹽度而改變，鹽度越大，黏著力越大。Purple membranes (PM) are the two-dimensional structure composed of Bacteriorhodopsin (BR) and many type's lipids. When PM is lighted, the proton transfers from cytoplasmic (CP) to extracellular (EC). Thus, the proton concentration gradient will be formed between CP and EC and then the photoelectric current is generated.CP and EC surfaces have different characteristics because they have different compositions. The observations were made by AFM.The fixed direction of PM adsorption on the substrate can be controlled by different processes. We found that the adhesion force of EC surface is slightly stronger than CP surface by Force-distance Curve analysis. The salt concentration also was found to affect the adhesion force. The salt concentration is higher, the adhesion force is stronger.