Radcliffe R, Nemerson Y
J Biol Chem. 1976 Aug 25;251(16):4749-802.
Coagulation Factor VII from bovine plasma is a glycoprotein containing a single peptide chain. The NH2-terminal sequence of Ala-Asx-Gly-Phe-Leu- is homologous with the NH2 termini of prothrombin, Factor IX, and the light chain of Factor X. Factor Xa in the presence of calcium ions and phospholipid cleaves Factor VII at an Arg-Ile bond in the sequence Arg-Ile-Val-Gly-Gly-, producing a two-chain molecule with at least 85 times the coagulant activity of single-chain Factor VII and a new NH2-terminal sequence homologous with the corresponding chains of thrombin, Factor IXa and Factor Xa. A second slower cleavage at an Arg-Gly bond destroys Factor VII activity. Bovine Factor VII, unlike prothrombin, Factor IX, and Factor X, is rapidly inhibited by diisopropylphosphorofluoridate (iPr2PF). [3H]iPr2PF is readily incorporated into one-chain, two-chain, and three-chain forms of Factor VII up to ratios of approximately 0.9 moles of [3H]diisopropylphosphate per mole of protein. The radioactive peptides generated from each form of [32P]iPr2PF-inhibited Factor VII by tryptic and thermolytic digestion were found to migrate together on paper electrophoresis. This indicates that the iPr2PF is incorporated stoichiometrically into the same specific site in each form.
牛血浆中的凝血因子VII是一种含有单条肽链的糖蛋白。其氨基末端序列Ala-Asx-Gly-Phe-Leu-与凝血酶原、因子IX以及因子X轻链的氨基末端同源。在钙离子和磷脂存在的情况下，因子Xa在序列Arg-Ile-Val-Gly-Gly-中的Arg-Ile键处切割因子VII，产生一种双链分子，其凝血活性至少是单链因子VII的85倍，并且具有与凝血酶、因子IXa和因子Xa相应链同源的新氨基末端序列。在Arg-Gly键处的第二次较慢切割会破坏因子VII的活性。与凝血酶原、因子IX和因子X不同，牛因子VII可被二异丙基氟磷酸酯（iPr2PF）迅速抑制。[3H]iPr2PF很容易以每摩尔蛋白质约0.9摩尔[3H]二异丙基磷酸酯的比例掺入因子VII的单链、双链和三链形式中。通过胰蛋白酶和热解消化从每种形式的[32P]iPr2PF抑制的因子VII产生的放射性肽在纸上电泳时一起迁移。这表明iPr2PF以化学计量方式掺入每种形式的相同特定位点。
