钙敏光蛋白水母发光蛋白和多管水母荧光素酶的比较研究

Comparative aspects of the calcium-sensitive photoproteins aequorin and obelin.

Moisescu D G, Ashley C C, Campbell A K

Biochim Biophys Acta. 1975 Jul 8;396(1):133-40. doi: 10.1016/0005-2728(75)90196-6.

Abstract

The calcium-dependency of the process of light emission has been investigated for the photoproteins aequorin and obelin. 2. The experimental curves of light production, expressed as a percentage of the maximal rate of utilisation, versus pCa are accurately predicted by the cooperative action of at least 2Ca-2+ for aequorin and at least 3Ca-2+ for obelin. 3. At low total monovalent cation concentrations, a pH change from 6.8 to 7.1 shifts the light production vs pCa curve by approx. 0.2 pCa units to the right for aequorin, while that for obelin is shifted by some 0.37 pCa units. 4. Other monovalent cations, such as Na+ are able to compete with Ca-2+ for the active sites of aequorin and also shift the light production vs pCa curve to the right. There is no apparent change in the calcium stoichiometry for light production under these conditions. 5. The same calcium stoichiometry for light emission was also obtained for aequorin or obelin in the presence of either unbuffered Ca-2+ solutions or of calcium/EGTA buffers.

摘要

已针对发光蛋白水母发光蛋白和海仙人掌发光蛋白研究了发光过程的钙依赖性。2. 以最大利用率百分比表示的光产生实验曲线与pCa的关系，对于水母发光蛋白而言，至少2个Ca²⁺的协同作用能准确预测该曲线，对于海仙人掌发光蛋白而言，至少3个Ca²⁺的协同作用能准确预测该曲线。3. 在低总单价阳离子浓度下，pH从6.8变为7.1会使水母发光蛋白的光产生与pCa曲线向右移动约0.2个pCa单位，而海仙人掌发光蛋白的该曲线会向右移动约0.37个pCa单位。4. 其他单价阳离子，如Na⁺，能够与Ca²⁺竞争水母发光蛋白的活性位点，也会使光产生与pCa曲线向右移动。在这些条件下，发光的钙化学计量比没有明显变化。5. 在存在未缓冲的Ca²⁺溶液或钙/乙二醇双乙酸盐缓冲液的情况下，水母发光蛋白或海仙人掌发光蛋白的发光钙化学计量比相同。