Abstract
我們研究壓力對白化綠豆下胚軸所取得之液泡腺核甘三磷酸水解酵素的影 響.在液泡膜上的腺核甘三磷酸水解酵素經壓力處理後,分解核甘三磷酸的 能力並未受到很明顯的影響,但其質子移入卻被抑制.然而純化之酵素水解 受質能力對壓力是敏感的.其相對活性會隨著壓力的增加而降低.我們也研 究壓力對此酵素的Michaelis常數及最大速率的影響;結果,壓力使兩個質 均降低.此酵素生理上的受質會使壓力更敏感;其它核酸均能提供某種程度 的保護作用.由各種光譜的研究,壓力可造成酵素結構上的改變. The effects of hydrostatic pressure on the integrity and function of tonoplast ATPase isolated from etiolated mung bean seedlings were investigated. When the membrane-bound tonoplast ATPase was subjected to hydrostatic pressure, the activity of ATP hydrolysis was not greatly affected, whereas ATPase- mediated H+-translocation was markedly inhibited. Pressure treatment decreased both Vmax and Km which implies an increase of ATP binding affinity but decrease of the ATP hydrolysis activity. Physiology substrate, ATP, augmented the lost of enzymatic activity upon pressure treatment. However, ADP, AMP and Pi exerted substantial protective effects against hydrosatic pressure. The conformational change of solubilized ATPase induced by hydrostatic pressure was futher determined by spectroscopic techniques. A decrease in polarization with pressure was observed. It is suggested that inactivation of solubilized tonoplast ATPase by pressure was resulted from protein dissociation.