Dwivedi A M, Woodeshick R W, Walton H L, Reilly T M
Du Pont Merck Pharmaceutical Company, Wilmington, DE 19880-0400.
Biochem Biophys Res Commun. 1991 Mar 15;175(2):437-43. doi: 10.1016/0006-291x(91)91583-x.
Recombinant plasminogen activator inhibitor-1 (rPAI-1) purified from Escherichia coli, like its natural counterpart, can exist in either active or latent form. To elucidate the structural basis for these two forms, both active and latent rPAI-1 have been studied using ultra-violet (UV), circular dichroism (CD), and fluorescence spectroscopy. The secondary structures determined by CD show no significant differences and indicate that both the forms are predominantly alpha helical and random. The UV spectra are also very similar with absorption maxima around 278 nm. The structures of the two forms were further characterized by measuring tryptophan fluorescence emissions and their quenching with ionic (iodide) and neutral (acrylamide) quenchers. These data indicate clear differences in the tertiary structures of the two forms with the latent form being more compact and folded in comparison with the active form.
从大肠杆菌中纯化得到的重组纤溶酶原激活物抑制剂-1（rPAI-1），与其天然对应物一样，能够以活性形式或潜伏形式存在。为了阐明这两种形式的结构基础，已使用紫外（UV）、圆二色性（CD）和荧光光谱对活性和潜伏形式的rPAI-1进行了研究。通过CD测定的二级结构没有显著差异，表明这两种形式主要都是α螺旋和无规卷曲。紫外光谱也非常相似，吸收最大值在278nm左右。通过测量色氨酸荧光发射及其用离子型（碘化物）和中性型（丙烯酰胺）猝灭剂的猝灭作用，进一步表征了这两种形式的结构。这些数据表明两种形式的三级结构存在明显差异，潜伏形式比活性形式更紧凑且折叠程度更高。
