Antuch W, Güntert P, Billeter M, Hawthorne T, Grossenbacher H, Wüthrich K
Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule-Hönggerberg, Zürich, Switzerland.
FEBS Lett. 1994 Sep 26;352(2):251-7. doi: 10.1016/0014-5793(94)00941-4.
The solution structure of the recombinant tick anticoagulant protein (rTAP) was determined by 1H nuclear magnetic resonance (NMR) spectroscopy in aqueous solution at pH 3.6 and 36 degrees C. rTAP is a 60-residue protein functioning as a highly specific inhibitor of the coagulation protease factor Xa, which was originally isolated from the tick Ornithodoros moubata. Its regular secondary structure consists of a two-stranded antiparallel beta-sheet with residues 22-28 and 32-38, and an alpha-helix with residues 51-60. The relative orientation of these regular secondary structure elements has nearly identical counterparts in the bovine pancreatic trypsin inhibitor (BPTI). In contrast, the loop between the beta-sheet and the C-terminal alpha-helix as well as the N-terminal 20-residue segment preceding the beta-sheet adopt different three-dimensional folds in the two proteins. These observations are discussed with regard to the implication of different mechanisms of protease inhibition by rTAP and by Kunitz-type protein proteinase inhibitors.
重组蜱抗凝蛋白（rTAP）的溶液结构是通过在pH 3.6和36℃的水溶液中用1H核磁共振（NMR）光谱测定的。rTAP是一种由60个残基组成的蛋白质，作为凝血蛋白酶因子Xa的高度特异性抑制剂发挥作用，它最初是从蜱类钝缘蜱中分离出来的。其规则的二级结构由包含22 - 28位和32 - 38位残基的双链反平行β-折叠以及包含51 - 60位残基的α-螺旋组成。这些规则二级结构元件的相对取向在牛胰蛋白酶抑制剂（BPTI）中有几乎相同的对应物。相比之下，β-折叠和C端α-螺旋之间的环以及β-折叠之前的N端20个残基片段在这两种蛋白质中呈现出不同的三维折叠。就rTAP和库尼茨型蛋白酶抑制剂对蛋白酶抑制的不同机制的影响对这些观察结果进行了讨论。
