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蛋白质的生物合成（ biosynthesis of protein ）

蛋白质的生物合成（ biosynthesis of protein ）. Concept of biosynthesis of protein. Protein biosynthesis also called translation, in the process, mRNA as templates be used to synthesize protein, according to genetic code in the mRNA molecule. The process. （ 1 ） activation of amino acid

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蛋白质的生物合成（ biosynthesis of protein ）

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  1. 蛋白质的生物合成（biosynthesis of protein）

  2. Concept of biosynthesis of protein Protein biosynthesis also called translation, in the process, mRNA as templates be used to synthesize protein, according to genetic code in the mRNA molecule.

  3. The process （1）activation of amino acid （2）biosynthesis of peptide chain （3）process and transport of peptide chain

  4. first segmentsynthesis system of protein

  5. synthesis system of protein • 20 amino acids • mRNA • tRNA • ribosome • Enzyme and protein factors • ATP、GTP • Mg2+、 K+

  6. 5 3 3’- non-transplate area 5’-non-transplate area open reading frame Start of genetic message End Tail Cap Ⅰ mRNA--direct template • Basic structure of mRNA

  7. 3 5 PPP protein 5 mG - 3 PPP AAA … protein Ribosome binding site Non-coding sequence Coding sequence initiator codon Stop codon • polycistron of prokaryotes • monocistron of eukaryotes

  8. Genetic code • codon 在mRNA的开放阅读框架区，以每3个相邻的核苷酸为一组，代表一种氨基酸(或其他信息)，这种三联体形式的核苷酸序列称为密码子。 • initiation codonand termination codon initiation codon：AUG termination codon ：UAA、UAG、UGA

  9. Genetic code

  10. 读码方向 5′ 3′ N C 肽链延伸方向 • Characteristic of genetic code 1. directional 翻译时遗传密码的阅读方向是5’→3’，即读码从mRNA的起始密码子AUG开始，按5’→3’的方向逐一阅读，直至终止密码子。

  11. 5’…….A U GG C AG U AC A U …… U A A 3’ 终止密码 Ala Val His Met 2. non-punctuated 编码蛋白质氨基酸序列的各个三联体密码连续阅读，密码子及密码子的各碱基之间既无间隔也无交叉。

  12. 缬 丙 酪 甘 缬 丙 丝 精 缬 脯 苏 天冬 基因损伤引起mRNA阅读框架内的碱基发生插入或缺失，可能导致框移突变(frameshift mutation)。

  13. 3. degenerate 一种氨基酸可具有2个或2个以上的密码子为其编码。这一特性称为遗传密码的简并性。 除色氨酸和甲硫氨酸仅有1个密码子外，其余氨基酸有2、3、4个或多至6个三联体为其编码。为同一种氨基酸编码的各密码子称为简并性密码子，也称同义密码子 。

  14. 4. universal 从简单的病毒到高等的人类，几乎使用同一套遗传密码，因此，遗传密码表中的这套“通用密码”基本上适用于生物界的所有物种，具有通用性。 密码的通用性进一步证明各种生物进化自同一祖先。

  15. 5. wobble 反密码子与密码子之间的配对有时并不严格遵守常见的碱基配对规律，这种现象称为摆动配对(wobble base pairing)。

  16. Wobble 3 2 1 U 1 2 3

  17. Ⅱ ribosome—place of synthesis of protein • Constituents of ribosome rRNA Many kinds of proteins

  18. ribosome constituent in different cells

  19. Ribosome in prokaryotes

  20. ⅢtRNA--carrier of amino acids

  21. conformation of tRNA 氨基酸臂 反密码环 二级结构 三级结构

  22. Ⅳ enzymes and factors 1. Significant enzymes • Aminoacyl-tRNA synthetase: catalyze the activation of amino acids. • Peptidase: catalyze the transfer of peptide from P site to A site. • Translocase:catalyze the transfer of ribosome to next genetic code,that is A site.

  23. 2. Protein factors • 起始因子（initiation factor，IF） • 延长因子（elongation factor，EF） • 释放因子（release factor，RF）

  24. The functions and classes of protein factors in prokaryotes

  25. The functions and classes of protein factors in eukaryotes

  26. 3. Substance of energy source and ion • Energy substance:ATP and GTP; • Ion: Mg2+、K+ .

  27. Second segmentactivation of amino acids

  28. aminoacyl-tRNA synthetase Amino acid + tRNA aminoacyl- tRNA AMP＋PPi ATP Ⅰ activation:conversion of amino acid to aminoacyl-tRNA • Process

  29. Presentation of aminoacyl-tRNA 氨基酸的三字母缩写-tRNA氨基酸的三字母缩写 例如： 丙氨酰-tRNA：Ala-tRNAAla 精氨酰-tRNA：Arg-tRNAArg 甲硫氨酰-tRNA：Met-tRNAMet

  30. Eukaryote • Start aminoacyl-tRNA: Met-tRNAiMet • Extended peptide chain :Met-tRNAMet • Prokaryote • Start aminoacyl-tRNA: fMet-tRNAifMet

  31. fMet-tRNAfMet的生成是一碳化合物转移和利用的过程之一，反应由转甲酰基酶催化，甲酰基从N10-甲酰四氢叶酸转移到甲硫氨酸的α-氨基上。

  32. Third segmentBiosynthesis of peptide chains

  33. Ⅰ prokaryote • 起始(initiation) • 延长(elongation) • 终止(termination ) • The process includes ：

  34. 1. initiation (1) separation of large subunit and small subunit of ribosome; (2) mRNA attached to the small subunit； (3) Initiation aminoacyl-tRNA attached to the small subunit； (4) The large subunit attached.

  35. (1) separation of large subunit and small subunit of ribosome IF-1 IF-3

  36. 5' 3' A U G (2) mRNA attached to the small subunit IF-1 IF-3

  37. IF-2 GTP 5' 3' A U G (3) Initiation aminoacyl-tRNA attached to the small subunit IF-1 IF-3

  38. 5' 3' A U G (4) The large subunit attached to form the initiation complex IF-2 GTP Pi GDP IF-1 IF-3

  39. IF-2 GTP 5' 3' A U G The process of initiation complex IF-2 Pi -GTP GDP IF-3 IF-1

  40. 2. elongation • ribosomal cycle： (1) 进位(positioning)/注册(registration) (2) 成肽(peptide bond formation) (3) 转位(translocation) • Every cycle will increase an amino acid on the peptide chain.

  41. 5' 3' A U G (1) positioning GTP Tu Ts Ts Tu GDP GTP

  42. (2) peptide bond formation

  43. (3) translocation

  44. positioning peptide bond formation translocation • The process of ribosome cycle

  45. 3. termination

  46. Fourth segmentprotein posttranslational modification and transport

  47. the macromolecule with the functions of promoting peptide chain fold: Ⅰ peptide chain fold to native conformation of protein • molecular chaperon • protein disulfide isomerase, PDI 3. peptide prolyl-cis-trans isomerase, PPI

  48. molecular chaperon (1) 热休克蛋白(heat shock protein, HSP) (2) 伴侣蛋白(chaperonin)

  49. ATP酶 肽链结合结构域 EEVD-COOH H2N Grp E 结合部位 DnaJ/HSP40 结合部位 (1) 大肠杆菌的HSP70 (DnaK) • 它有两个主要功能域：一个是存在于N-端的高度保守的ATP酶结构域，能结合和水解ATP；另一个是存在于C-端的多肽链结合结构域。蛋白质的折叠需要这两个结构域的相互作用。

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