Kotormán M, Laczkó I, Szabó A, Simon L M
Department of Biochemistry, Faculty of Science, University of Szeged, P.O. Box 533, H-6701, Szeged, Hungary.
Biochem Biophys Res Commun. 2003 Apr 25;304(1):18-21. doi: 10.1016/s0006-291x(03)00534-5.
The effects of calcium ions on the conformation and catalytic activity of trypsin and alpha-chymotrypsin were studied in aqueous ethanol. The activity of alpha-chymotrypsin was practically lost within 10 min in the presence of 60% ethanol while trypsin preserved about 40% of its original activity even in 85% ethanol at pH 3. The catalytic activity of alpha-chymotrypsin did not decrease in the presence of 1.2M CaCl2 and 0.6M CaCl2 with trypsin in ethanolic solvent. In the latter case an activation of enzyme was observed. The stabilizing effects of calcium ions were accompanied by an increase in the helical content in both enzymes, as followed by circular dichroism measurements.
在乙醇水溶液中研究了钙离子对胰蛋白酶和α-糜蛋白酶的构象及催化活性的影响。在60%乙醇存在的情况下，α-糜蛋白酶的活性在10分钟内几乎丧失，而即使在pH值为3的85%乙醇中，胰蛋白酶仍保留约40%的原始活性。在乙醇溶剂中，1.2M氯化钙和0.6M氯化钙存在时，α-糜蛋白酶的催化活性并未降低，而胰蛋白酶则出现了酶激活现象。圆二色性测量结果表明，钙离子的稳定作用伴随着两种酶中螺旋含量的增加。
