Negrete-Abascal E, Tenorio V R, Serrano J J, Garcia C, de la Garza M
Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, México D.F., Mexico.
Can J Vet Res. 1994 Apr;58(2):83-6.
It was found that 48 hour cultures of Actinobacillus pleuropneumoniae secreted proteases into the medium. Electrophoresis in polyacrylamide gels (10%) copolymerized with porcine gelatin (0.1%), of the 70% (NH4)2SO4 precipitate from the culture supernatants, displayed protease activities of different molecular weights: > 200, 200, 90, 80, 70 and 50 kDa. They had activity over a broad range of pHs (4-8), with an optimal pH of 6-7. All were inhibited by 10 mM EDTA, and reactivated by 10 mM calcium. They were stable at -20 degrees C for more than a month. The proteases also degraded porcine IgA and porcine, human, and bovine hemoglobin, although they appeared to be less active against the hemoglobins. The IgA was totally cleaved in 48 h, using supernatants concentrated with polyvinyl pyrrolidone or the 70% (NH4)2SO4. Extracellular proteases could play a role in virulence.
研究发现，胸膜肺炎放线杆菌培养48小时后会向培养基中分泌蛋白酶。对培养上清液的70%硫酸铵沉淀物在与0.1%猪明胶共聚的10%聚丙烯酰胺凝胶中进行电泳，结果显示出不同分子量的蛋白酶活性：大于200 kDa、200 kDa、90 kDa、80 kDa、70 kDa和50 kDa。它们在较宽的pH范围（4 - 8）内具有活性，最适pH为6 - 7。所有蛋白酶均被10 mM EDTA抑制，并可被10 mM钙重新激活。它们在-20℃下可稳定保存一个多月。这些蛋白酶还能降解猪IgA以及猪、人、牛血红蛋白，不过它们对血红蛋白的活性似乎较低。使用聚乙烯吡咯烷酮浓缩的上清液或70%硫酸铵，IgA在48小时内会被完全裂解。细胞外蛋白酶可能在毒力方面发挥作用。
