Fujiyama Y, Iwaki M, Hodohara K, Hosoda S, Kobayashi K
Mol Immunol. 1986 Feb;23(2):147-50. doi: 10.1016/0161-5890(86)90036-2.
Fc fragments of human immunoglobulin A(IgA) of IgA1 subclass and IgA2 subclass of A2m(1) allotype were prepared from IgA paraproteins by digestion with a protease from Clostridium sp. (M.O.-6). The N-terminal tetrapeptide of Val-Pro-Ser-Thr- for the Fc of IgA1 subclass, and that of Val-Pro-Pro-Pro- for the Fc of IgA2:A2m(1) allotype, were identified by sequence analysis. The site of cleavage by the protease was defined to be at the Pro-Val peptide bond, which is a common peptide bond present at 221-222 in both alpha chains. IgA of IgA2 subclass of A2m(2) allotype is resistant to the protease due to the different, Arg-Val, peptide bond at the same position.
通过用来自梭菌属（M.O.-6）的蛋白酶消化IgA副蛋白，从人免疫球蛋白A（IgA）的IgA1亚类和A2m(1)同种异型的IgA2亚类制备Fc片段。通过序列分析鉴定出IgA1亚类Fc的N端四肽为Val-Pro-Ser-Thr-，以及IgA2:A2m(1)同种异型Fc的N端四肽为Val-Pro-Pro-Pro-。蛋白酶的切割位点被确定为Pro-Val肽键，这是两条α链中221-222位存在的一个共同肽键。由于在相同位置的肽键不同，即Arg-Val，A2m(2)同种异型的IgA2亚类IgA对该蛋白酶具有抗性。
