Protein synthesis process

2.1 activation and transferration of amino acid

Diagram of aminoacyl-tRNA synthetase

Step 1 of reaction

     aa＋ATP-E—→ aminoacyl-AMP-E＋ PPi

Step 2

★Generation of amino-acyl tRNA 

★catalyzed by 

★amino-acyl tRNA 

★synthetase

★氨基酰-tRNA的合成

b.  Aminoacyl-tRNA synthetase特点

★1. high specificity to substrate-amino acid.

★2.proofreading activity（校正活性，水解位点），第二套密码系统—tRNA。

2.2  Ribosome cycle（核糖体循环-原核）

★Protein synthesis initiates from AUG at 5’ end and decipher genetic codons to polymerize aa residues until stop codon occurs.

★Translation process：

翻译起始位点识别 — SD sequence 

1. initiation

★翻译起始复合物 (translational initiation complex) = mRNA + initiation aminoacyl-tRNA + ribosome

 substrate + initiation factor + GTP + Mg2+

★Formation of translational initiation complex in prokaryote-形成翻译起始复合物

  ·（1）Ribosome acitivation

  ·（2）30S- initiation complex

  ·（3）70S- initiation complex