Valentini G, Stoppini M, Iadarola P, Malcovati M, Ferri G, Speranza M L
Dipartimento di Biochimica, Università di Pavia.
Biol Chem Hoppe Seyler. 1993 Jan;374(1):69-74. doi: 10.1515/bchm3.1993.374.1-6.69.
Pyridoxal 5'-phosphate incorporation into pyruvate kinase II from E. coli was decreased by the substrate phosphoenolpyruvate and increased by the allosteric activator ribose 5-phosphate, the total incorporation being linearly related to inactivation. Four lysyl residues were substantially modified, whatever the incubation conditions were while two additional residues became reactive only in the presence of the allosteric activator. Six tryptic peptides containing modified lysines were purified and sequenced. They defined five regions of pyruvate kinase II, since one of them contained two labelled lysines and included a peptide which also appeared independently. Sequence comparison with E. coli type I, yeast and cat muscle pyruvate kinases shows that the binding regions of pyruvate kinase II are clearly divergent from those of pyruvate kinase I and of the eukaryotic enzymes.
磷酸吡哆醛掺入大肠杆菌丙酮酸激酶II的过程，会被底物磷酸烯醇丙酮酸降低，并被变构激活剂5-磷酸核糖增加，总掺入量与失活呈线性相关。无论孵育条件如何，四个赖氨酸残基都会被显著修饰，而另外两个残基仅在变构激活剂存在时才具有反应性。纯化并测序了六个含有修饰赖氨酸的胰蛋白酶肽段。它们确定了丙酮酸激酶II的五个区域，因为其中一个区域包含两个标记的赖氨酸，并且包含一个也独立出现的肽段。与大肠杆菌I型、酵母和猫肌肉丙酮酸激酶的序列比较表明，丙酮酸激酶II的结合区域与丙酮酸激酶I和真核酶的结合区域明显不同。
