Enjyoji K, Miyazaki K, Kato H
National Cardiovascular Center Research Institute, Osaka University.
J Biochem. 1991 Jun;109(6):890-8. doi: 10.1093/oxfordjournals.jbchem.a123476.
We have found that rat plasma corrected the non-activated PT of human normal or factor-X deficient plasma, and the factor Xa-like activity being constantly detected in every 1 ml of blood collected via the cannulated carotid artery of rats. The present study was undertaken to characterize the factor Xa-like activity in rat plasma by preparing rat factor X and a monoclonal antibody against it. Factor X was purified from a BaCl2 eluate of rat plasma by chromatographies on columns of DEAE-Sepharose CL-6B and Sulfate Cellulofine or on a column of Affi-Gel 10 conjugated with a monoclonal antibody against rat factor X. Factor Xa-like activity in rat plasma was eliminated by the treatment of rat plasma with a monoclonal antibody which recognized the heavy chain portions of rat factors X and Xa. A kinetical study demonstrated that rat factor Xa was strongly inhibited by rat antithrombin III, with a Ki of 2.2 x 10(-11) M, in the presence of heparin. However, in the absence of heparin, the second order rate constant for the inhibition of rat factor Xa by rat antithrombin III was 2.6 x 10(4) M-1.min-1, which was one forty-third that for the inhibition of human factor Xa by human antithrombin III. Furthermore, rat factor Xa was resistant to the inhibition by rat alpha-1-antitrypsin and alpha-2-macroglobulin.(ABSTRACT TRUNCATED AT 250 WORDS)
我们发现，大鼠血浆可校正人正常血浆或因子X缺乏血浆的非活化凝血酶原时间，并且在通过大鼠颈总动脉插管采集的每毫升血液中持续检测到因子Xa样活性。本研究旨在通过制备大鼠因子X及其单克隆抗体来表征大鼠血浆中的因子Xa样活性。通过在DEAE-琼脂糖CL-6B柱和硫酸纤维素柱上或在与抗大鼠因子X单克隆抗体偶联的Affi-Gel 10柱上进行色谱分离，从大鼠血浆的BaCl2洗脱液中纯化因子X。用识别大鼠因子X和Xa重链部分的单克隆抗体处理大鼠血浆，可消除大鼠血浆中的因子Xa样活性。动力学研究表明，在肝素存在下，大鼠抗凝血酶III对大鼠因子Xa有强烈抑制作用，Ki为2.2×10(-11)M。然而，在没有肝素的情况下，大鼠抗凝血酶III抑制大鼠因子Xa的二级速率常数为2.6×10(4)M-1·min-1，是人抗凝血酶III抑制人因子Xa的速率常数的四十三分之一。此外，大鼠因子Xa对大鼠α1-抗胰蛋白酶和α2-巨球蛋白的抑制具有抗性。（摘要截断于250字）
