Lambin P, Nadal C, Winchenne J J, Boffa G A
C R Acad Sci III. 1987;304(19):477-80.
Inhibitory effect on the G1-S transition of hepatocytes in vivo was measured in the ultrafiltrates of alpha 2 M/trypsin and alpha 2 M/thrombin complexes (alpha 2 macroglobulin: alpha 2 M). Untreated human alpha 2 M activity corresponds to one inhibitory unit/mg. When alpha 2 M/trypsin and alpha 2 M/thrombin complexes were ultrafiltrated at pH 7.8 on PM 10 Amicon membrane, 300 inhibitory units were obtained from 1 mg of alpha 2 M. After treatment at pH 10 of the same complexes, 30,000 inhibitory units were obtained from the same quantity of alpha 2 M. Such a high activity was observed when native alpha 2 M was used before alpha 2 M/enzyme interaction. When alpha 2 M was previously treated by an aliphatic amine or reduced and alkylated, the activity found in ultrafiltrates was very low. In the same way, a low activity was observed when the captation capacity of alpha 2 M was exceeded. These results show that specific cleavages on alpha 2 M molecule are needed to obtain a large amount of active inhibitory peptide.
在α2M/胰蛋白酶和α2M/凝血酶复合物（α2巨球蛋白：α2M）的超滤液中测定了其对体内肝细胞G1-S期转变的抑制作用。未经处理的人α2M活性相当于1个抑制单位/毫克。当α2M/胰蛋白酶和α2M/凝血酶复合物在pH 7.8条件下于PM 10 Amicon膜上进行超滤时，从1毫克α2M中可获得300个抑制单位。在相同复合物于pH 10处理后，相同量的α2M可获得30,000个抑制单位。当在α2M/酶相互作用之前使用天然α2M时观察到如此高的活性。当α2M预先用脂肪胺处理或还原并烷基化时，超滤液中发现的活性非常低。同样，当α2M的捕获能力被超过时也观察到低活性。这些结果表明，需要对α2M分子进行特定切割才能获得大量活性抑制肽。
