Käck H, Sandmark J, Gibson K J, Schneider G, Lindqvist Y
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Protein Sci. 1998 Dec;7(12):2560-6. doi: 10.1002/pro.5560071209.
The crystal structures of two complexes of dethiobiotin synthetase, enzyme-diaminopelargonic acid-MgADP-AlF3 and enzyme-dethiobiotin-MgADP-Pi, respectively, have been determined to 1.8 A resolution. In dethiobiotin synthetase, AlF3 together with carbamylated diaminopelargonic acid mimics the phosphorylated reaction intermediate rather than the transition state complex for phosphoryl transfer. Observed differences in the binding of substrate, diaminopelargonic acid, and the product, dethiobiotin, suggest considerable displacements of substrate atoms during the ring closure step of the catalytic reaction. In both complexes, two metal ions are observed at the active site, providing evidence for a two-metal mechanism for this enzyme.
已分别将脱硫生物素合成酶的两种复合物（酶 - 二氨基壬酸 - MgADP - AlF3和酶 - 脱硫生物素 - MgADP - 磷酸）的晶体结构解析到1.8埃的分辨率。在脱硫生物素合成酶中，AlF3与氨甲酰化二氨基壬酸一起模拟磷酸化反应中间体，而非磷酰转移的过渡态复合物。观察到底物二氨基壬酸和产物脱硫生物素在结合上的差异，表明在催化反应的闭环步骤中底物原子发生了相当大的位移。在这两种复合物中，活性位点均观察到两个金属离子，为该酶的双金属机制提供了证据。
