Huang Kevin S, Weinger Joshua S, Butler Ethan B, Strobel Scott A
Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, USA.
J Am Chem Soc. 2006 Mar 15;128(10):3108-9. doi: 10.1021/ja0554099.
The ribosomal peptidyl transferase center is expected to be regiospecific with regard to its tRNA substrates, yet the ester linkages between the tRNA and the amino acid or peptide are susceptible to isomerization between the O2' and O3' hydroxyls of the terminal A76 ribose sugar. To establish which isomer of the P site tRNA ester is utilized by the ribosome, we prepared two nonisomerizable transition state inhibitors with either an A76 O2' or O3' linkage. Strong preferential binding to the O3' regioisomer indicates that the peptidyl transferase proceeds through a transition state with an O3'-linked peptide in the P-site.
核糖体肽基转移酶中心预计对其tRNA底物具有区域特异性，然而tRNA与氨基酸或肽之间的酯键易在末端A76核糖的O2'和O3'羟基之间发生异构化。为确定核糖体利用的P位点tRNA酯的哪种异构体，我们制备了两种具有A76 O2'或O3'连接的不可异构化过渡态抑制剂。对O3'区域异构体的强烈优先结合表明肽基转移酶通过P位点中具有O3'连接肽的过渡态进行反应。
