Acuña A U, González-Rodríguez J, Lillo M P, Naqvi K R
Biophys Chem. 1987 Apr;26(1):55-61. doi: 10.1016/0301-4622(87)80007-8.
Two fluorescent derivatives of human fibrinogen have been synthesized, by the covalent bonding of 1-dimethylaminoaphthalene-5-sulphonyl and methylpyrene chromophores, to investigate the internal molecular dynamics of the protein in solution. The stationary fluorescence depolarization of these derivatives under isothermal conditions is described here while in an accompanying paper (part II) a time-resolved study is reported. From the static fluorescence data it is concluded that reorientational processes in the subnanosecond and microsecond time ranges account for all the observed depolarization. The faster motion was assigned to the restricted, localized oscillations of the label while the slow motion was ascribed to the overall rotation of the protein molecule. Consequently, the protein in solution appears considerably rigid in the 10-1000 ns range, in contrast with a previous conception of a flexible fibrinogen based on non-isothermal depolarization experiments. These previous experiments are, in fact, concordant with the rigid fibrinogen proposed here if they are reinterpreted using Weber's early ideas on thermally activated depolarization (G. Weber, J. Biochem. 51 (1952) 145).
已通过1-二甲基氨基萘-5-磺酰基和甲基芘发色团的共价键合合成了两种人纤维蛋白原的荧光衍生物，以研究该蛋白质在溶液中的内部分子动力学。本文描述了这些衍生物在等温条件下的稳态荧光去极化，而在一篇配套论文（第二部分）中报道了一项时间分辨研究。从静态荧光数据可以得出结论，亚纳秒和微秒时间范围内的重取向过程解释了所有观察到的去极化现象。较快的运动归因于标记物的受限局部振荡，而较慢的运动归因于蛋白质分子的整体旋转。因此，与之前基于非等温去极化实验得出的纤维蛋白原是柔性的概念相反，溶液中的蛋白质在10-1000纳秒范围内显得相当刚性。实际上，如果使用韦伯早期关于热激活去极化的观点（G. Weber，《生物化学杂志》51 (1952) 145）重新解释之前的这些实验，它们与这里提出的刚性纤维蛋白原是一致的。
