Blom N S, Tétreault S, Coulombe R, Sygusch J
Départment de biochimie, Université de Montréal, Canada.
Nat Struct Biol. 1996 Oct;3(10):856-62. doi: 10.1038/nsb1096-856.
The molecular architecture of the Class II E. coli fructose 1,6-bisphosphate aldolase dimer was determined to 1.6 A resolution. The subunit fold corresponds to a singly wound alpha/beta-barrel with an active site located on the beta-barrel carboxyl side of each subunit. In each subunit there are two mutually exclusive zinc metal ion binding sites, 3.2 A apart; the exclusivity is mediated by a conformational transition involving side-chain rotations by chelating histidine residues. A binding site for K+ and NH4+ activators was found near the beta-barrel centre. Although Class I and Class II aldolases catalyse identical reactions, their active sites do not share common amino acid residues, are structurally dissimilar, and from sequence comparisons appear to be evolutionary distinct.
已确定II类大肠杆菌1,6-二磷酸果糖醛缩酶二聚体的分子结构，分辨率为1.6埃。亚基折叠对应于一个单绕α/β桶，活性位点位于每个亚基的β桶羧基侧。在每个亚基中有两个相互排斥的锌金属离子结合位点，相距3.2埃；这种排斥性是由一种构象转变介导的，该转变涉及螯合组氨酸残基的侧链旋转。在β桶中心附近发现了K⁺和NH₄⁺激活剂的结合位点。尽管I类和II类醛缩酶催化相同的反应，但它们的活性位点不共享共同的氨基酸残基，结构不同，并且从序列比较来看似乎在进化上是不同的。
