Wolff C, Lai C S
Department of Radiology, Medical College of Wisconsin, Milwaukee 53226.
Biochemistry. 1988 May 3;27(9):3483-7. doi: 10.1021/bi00409a053.
A fluorescence energy transfer technique has been used to study the intramolecular distance between the two amino termini of human plasma fibronectin. The glutamine-3 residue near the amino terminus of each chain was labeled enzymatically with either monodansylcadaverine or monofluoresceinylcadaverine by use of coagulation factor XIIIa. The nonradiative fluorescence energy transfer between the dansyl (donor) and fluorescein (acceptor) pair in the same protein molecule was determined from steady-state fluorescence measurements. On the basis of the transfer efficiency of 78%, the intramolecular distance between two glutamine-3 residues of fibronectin was estimated to be approximately 23 A, suggesting that the two amino termini of plasma fibronectin are in close proximity. High salt, which affects the hydrodynamic properties of the protein, has no effect on the measured distance. The results support the contention that both compact (in low salt) and expanded (in high salt) conformers of fibronectin are relatively spherical in shape.
一种荧光能量转移技术已被用于研究人血浆纤连蛋白两个氨基末端之间的分子内距离。通过凝血因子ⅩⅢa，每条链氨基末端附近的谷氨酰胺-3残基被酶法用单丹磺酰尸胺或单荧光素酰尸胺标记。通过稳态荧光测量确定同一蛋白质分子中丹磺酰（供体）和荧光素（受体）对之间的非辐射荧光能量转移。基于78%的转移效率，纤连蛋白两个谷氨酰胺-3残基之间的分子内距离估计约为23埃，这表明血浆纤连蛋白的两个氨基末端彼此靠近。影响蛋白质流体动力学性质的高盐对所测距离没有影响。结果支持了这样的观点，即纤连蛋白的紧密构象（低盐时）和伸展构象（高盐时）形状都相对呈球形。
