Sygusch J, Beaudry D
Biochem Biophys Res Commun. 1985 Apr 16;128(1):417-23. doi: 10.1016/0006-291x(85)91695-x.
Catalytically active crystals of rabbit skeletal muscle aldolase are inactivated by phosphate ion and D-glyceraldehyde-3-phosphate. Four moles of phosphate are incorporated per mole of tetrameric enzyme. The inactivation rates are first order in time and demonstrate saturation behaviour. Competition inactivation experiments are consistent with the two substrates competing for the same site on the enzyme. Protection is afforded by substrates binding to the active site on the enzyme. No phosphate inactivation is observed in solution under identical experimental conditions and D-glyceraldehyde-3-phosphate inactivation in solution is unaffected by phosphate ion concentrations. Inactivation by phosphate is apparently due to an unique enzyme conformation stabilized upon protein crystallization.
兔骨骼肌醛缩酶的催化活性晶体可被磷酸根离子和3-磷酸-D-甘油醛灭活。每摩尔四聚体酶结合4摩尔磷酸。失活速率呈一级反应动力学且表现出饱和行为。竞争失活实验表明这两种底物竞争酶上的同一位点。底物与酶活性位点的结合可提供保护作用。在相同实验条件下，溶液中未观察到磷酸根导致的失活，且溶液中3-磷酸-D-甘油醛的失活不受磷酸根离子浓度影响。磷酸根导致的失活显然是由于蛋白质结晶后形成的一种独特酶构象所致。
