Marsh H C, George E M, Koehler K A, Hiskey R G
Biochim Biophys Acta. 1981 Jan 30;667(1):35-43. doi: 10.1016/0005-2795(81)90064-7.
In order to assess the importance of a variety of environmental factors on the structure of bovine prothrombin fragment 1, we have examined acrylamide quenching of fragment 1 intrinsic fluorescence. Tryptophan exposure, determined from Stern-Volmer plots, is heterogeneous with one or more of the three fragment 1 tryptophans being exposed to solvent. In the presence of Ca2+ or Mg2+ even the most accessible tryptophan(s) are relatively buried. Only small differences in tryptophan exposure may exist between fragment 1-Ca2+ and fragment 1-Mg2+ complexes. Lowering pH, on the other hand, results in increased tryptophan exposure. Finally, structural isomers of fragment 1 which exist in the absence of metal ions have identical tryptophan exposure as determined by acrylamide quenching and fluorescence intensity.
为了评估多种环境因素对牛凝血酶原片段1结构的重要性，我们检测了片段1固有荧光的丙烯酰胺猝灭情况。从斯特恩-沃尔默图确定的色氨酸暴露情况是异质的，片段1的三个色氨酸中的一个或多个暴露于溶剂中。在Ca2+或Mg2+存在的情况下，即使是最易接近的色氨酸也相对被掩埋。片段1-Ca2+和片段1-Mg2+复合物之间色氨酸暴露可能仅存在微小差异。另一方面，降低pH值会导致色氨酸暴露增加。最后，在没有金属离子的情况下存在的片段1的结构异构体，通过丙烯酰胺猝灭和荧光强度测定，具有相同的色氨酸暴露情况。
