Szeltner Zoltán, Rea Dean, Juhász Tünde, Renner Veronika, Fülöp Vilmos, Polgár László
Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H-1518 Budapest 112, P.O. Box 7, Hungary.
J Mol Biol. 2004 Jul 9;340(3):627-37. doi: 10.1016/j.jmb.2004.05.011.
Prolyl oligopeptidase contains a peptidase domain and its catalytic triad is covered by the central tunnel of a seven-bladed beta-propeller. This domain makes the enzyme an oligopeptidase by excluding large structured peptides from the active site. The apparently rigid crystal structure does not explain how the substrate can approach the catalytic groups. Two possibilities of substrate access were investigated: either blades 1 and 7 of the propeller domain move apart, or the peptidase and/or propeller domains move to create an entry site at the domain interface. Engineering disulfide bridges to the expected oscillating structures prevented such movements, which destroyed the catalytic activity and precluded substrate binding. This indicated that concerted movements of the propeller and the peptidase domains are essential for the enzyme action.
脯氨酰寡肽酶含有一个肽酶结构域，其催化三联体被一个七叶β-螺旋桨的中央通道所覆盖。该结构域通过将大的结构化肽排除在活性位点之外，使该酶成为一种寡肽酶。表面上刚性的晶体结构无法解释底物如何接近催化基团。研究了底物进入的两种可能性：要么螺旋桨结构域的叶片1和叶片7分开，要么肽酶和/或螺旋桨结构域移动以在结构域界面处形成一个进入位点。在预期的振荡结构处构建二硫键会阻止这种移动，这会破坏催化活性并阻止底物结合。这表明螺旋桨结构域和肽酶结构域的协同运动对于酶的作用至关重要。
