Dewey T G, Datta M M
Department of Chemistry, University of Denver, Colorado 80208.
Biophys J. 1989 Aug;56(2):415-20. doi: 10.1016/S0006-3495(89)82687-6.
It is demonstrated that fluorescence resonance energy transfer may be used to determine the fractal dimension of aggregates of membrane-bound proteins. Theoretical and experimental results are presented for two different experimental designs: energy transfer between proteins and energy transfer from lipids to proteins. For energy transfer between proteins the lattice spacing must be known independently for a fractal dimension to be uniquely determined, and this represents a disadvantage to this experimental design. Results are presented for the calcium ATPase and a fractal dimension of 1.9 is estimated for ATPase aggregates by assuming a lattice spacing of 50 A. Energy transfer from lipids to protein provides a means of estimating the length of the "coast-line" of the aggregate. In this case the fractal dimension is uniquely determined from a log-log plot. An analysis of data for bacteriohodopsin reconstituted in phospholipid vesicles gives a fractal dimension of 1.6. The structural basis of the value for the fractal dimension is discussed for these two systems. These techniques provide a means of assessing the nature of protein-protein interactions in membranous systems.
结果表明，荧光共振能量转移可用于确定膜结合蛋白聚集体的分形维数。给出了两种不同实验设计的理论和实验结果：蛋白质之间的能量转移以及从脂质到蛋白质的能量转移。对于蛋白质之间的能量转移，为了唯一确定分形维数，必须独立知道晶格间距，这是该实验设计的一个缺点。给出了钙ATP酶的结果，通过假设晶格间距为50埃，估计ATP酶聚集体的分形维数为1.9。从脂质到蛋白质的能量转移提供了一种估计聚集体“海岸线”长度的方法。在这种情况下，分形维数可从双对数图中唯一确定。对磷脂囊泡中重组的细菌视紫红质的数据进行分析，得到分形维数为1.6。讨论了这两个系统中分形维数值的结构基础。这些技术提供了一种评估膜系统中蛋白质 - 蛋白质相互作用性质的方法。
