Matern H, Weiser U, Holzer H
Eur J Biochem. 1979 Nov;101(2):325-32. doi: 10.1111/j.1432-1033.1979.tb19724.x.
A heat-stable polypeptide has been detected in Saccharomyces carlsbergensis which inhibits specifically proteinase B from yeast. This proteinase B inhibitor IB3 differs substantially in chemical, physical and antigenic properties from the earlier described proteinase B inhibitors IB1 and IB2 from yeast. The inhibitor IB3 has been purified from S. carlsbergensis and appears to be homogeneous by disc gel electrophoresis and sodium dodecyl sulfate gel electrophoresis. The molecular weight has been estimated at 11 500, with no evidence for the existence of subunits. The amino acid analysis shows the absence of tryptophan. No compounds other than amino acids could be detected. The isoelectric point is 4.6. The inhibitor is not affected by incubation with proteinase B but is inactivated by proteinase A and carboxypeptidase Y from yeast and by trypsin from bovine pancreas. The proteinase B inhibitor association constant was calculated to be 3.3 x 10(9) M-1 and the enzyme inhibitor complex is stable at 25 degrees C in the pH range 5--10. The inhibitor does not exhibit immunological cross-reactivity with IB1 and IB2. After centrifugal fractionation at 40 000 x g of a metabolic lysate from spheroplasts the inhibitor was found to be localized in the supernatant, i.e. the extravacuolar soluble fraction.
在卡尔斯伯酵母中检测到一种热稳定多肽，它能特异性抑制酵母中的蛋白酶B。这种蛋白酶B抑制剂IB3在化学、物理和抗原特性上与早期描述的酵母蛋白酶B抑制剂IB1和IB2有很大不同。抑制剂IB3已从卡尔斯伯酵母中纯化出来，通过圆盘凝胶电泳和十二烷基硫酸钠凝胶电泳显示其似乎是均一的。估计其分子量为11500，没有亚基存在的证据。氨基酸分析表明不存在色氨酸。除氨基酸外未检测到其他化合物。其等电点为4.6。该抑制剂与蛋白酶B孵育不受影响，但会被酵母中的蛋白酶A和羧肽酶Y以及牛胰蛋白酶灭活。蛋白酶B抑制剂的缔合常数经计算为3.3×10⁹ M⁻¹，酶抑制剂复合物在25℃、pH值5 - 10范围内稳定。该抑制剂与IB1和IB2不存在免疫交叉反应。对原生质体代谢裂解物在40000×g下进行离心分级分离后，发现抑制剂定位于上清液中，即液泡外可溶性部分。
