REVERSIBLE THERMAL INACTIVATION OF THE QUINOPROTEIN GLUCOSE-DEHYDROGENASE FROM ACINETOBACTER-CALCOACETICUS - CA-2+ IONS ARE NECESSARY FOR RE-ACTIVATION
REVERSIBLE THERMAL INACTIVATION OF THE QUINOPROTEIN GLUCOSE-DEHYDROGENASE FROM ACINETOBACTER-CALCOACETICUS - CA-2+ IONS ARE NECESSARY FOR RE-ACTIVATION
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DOI：
10.1042/bj2610415
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发表时间：
1989-07-15
影响因子：
4.1
通讯作者：
GORISCH, H
中科院分区：
文献类型：
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作者：
GEIGER, O;GORISCH, H
来自乙酸钙不动杆菌的均质醌蛋白葡萄糖脱氢酶的可溶形式在高于 35%.ETA 的温度下可逆失活。活性酶和变性酶之间建立平衡，这取决于所用的蛋白质浓度和失活温度。热失活后，酶解离为辅基吡咯喹啉醌和葡萄糖脱氢酶的 apo 形式。 50% 灭活后。预计到达时间。活性酶在 25%.ETA 时再次重新形成。Ca2+ 离子对于重新激活过程是必需的。重新激活的速度取决于蛋白质浓度、辅基吡咯并喹啉醌的浓度和Ca2+浓度。可以分离apo形式的葡萄糖脱氢酶，并在吡咯喹啉醌和Ca2+存在下形成活性全酶。尽管天然葡萄糖脱氢酶在 EDTA 或反式 1,2-二氨基环己烷-NNN'' N''-四乙酸存在下不会失活，但 Ca2+ 可以稳定酶，防止热失活。葡萄糖脱氢酶的每个亚基有两个 Ca2+ 离子。数据表明吡咯喹啉醌通过 Ca2+ 桥结合在活性位点。 Mn2+和Cd2+可以取代再活化混合物中的Ca2+。
The soluble form of the homogeneous quinoprotein glucose dehydrogenase from Acinetobacter calcoaceticus is reversibly inactivated at temperatures above 35%.ETA.. An equilibrium is established between active and denatured enzyme, this depending on the protein concentration and the inactivation temperature used. Upon thermal inactivation the enzyme dissociates into the prosthetic group pyrroloquinoline quinone and the apo form of glucose dehydrogenase. After inactivation at 50%.ETA. active enzyme is re-formed again at 25%.ETA.. Ca2+ ions are necessary for the re-activation process. The velocity of re-activation depends on the protein concentration, the concentration of the prosthetic group pyrroloquinoline quinone and the Ca2+ concentration. The apo form of glucose dehydrogenase can be isolated, and in the presence of pyrroloquinoline quinone and Ca2+ active holoenzyme is formed. Even though native glucose dehydrogenase is not inactivated in the presence of EDTA or trans-1,2-diaminocyclohexane-NNN'' N''-tetra-acetic acid, Ca2+ stabilizes the enzyme against thermal inactivation. Two Ca2+ ions are found per subunit of glucose dehydrogenase. The data suggest that pyrroloquinoline quinone is bound at the active site via a Ca2+ bridge. Mn2+ and Cd2+ can replace Ca2+ in the re-activation mixture.