Enzyme Biocatalysts Cell Organella Enzyme Protein Immobilized biocatalysts
生物催化劑之定義及優點 • 定義 Enzyme Biocatalysts Cell Organella Enzyme: Protein Immobilized bio-catalysts
酵素的統一分類與EC編號 • EC 1: Oxido-reductase Sred + S’ox Sox + S’red • EC 2: Transferase S – G + S’ S’ – G +S • EC 3: Hydrolase • EC 4: Lyase • EC 5: Isomerase L- D- • EC 6: Ligase, Synthease
酵素之一般性質 • • • – – – 催化特性 催化效率? 基質特異性 (substrate specificity) Stereo-specificity 最適氫離子濃度 最適溫度 (Optimum temperature) 共軛因子 多為維生素 金屬離子 輔酵素: Holoenzyme = Apoenzyme + Coenzym 輔基質 (Cosubstrate): NAD+, NADP+, ATP, Co. A
酵素之一般性質 • 多量體酵素 – Monomeric enzyme – Oligomeric enzyme – Multienzyme complex • 阻礙劑 (Inhibitor) – 競爭性阻礙 (Competitive inhibition) – 非競爭性阻礙 (Noncompetitive inhibition • 賦活劑之作用 (Activator) • 酵素前驅體: 活性酵素名後加-ogen • 安定性 (Stability)
常用酵素之性質與用途 – 蛋白質分解酵素(Protease)又稱peptide hydrase • Endo-peptidase – Trypsin – Chymotrypsin • Exo-peptidase – Carboxypeptidase – Leucine aminopeptidase
酵素與切割位置 名稱 最佳 p. H � 切割位置 Chymotrypsin 7. 5 - 8. 5 C-terminal to M, I, S, T, V H, G, A Elastase 8. 0 - 8. 5 C-terminal side of G, A, S, V, L, I Endoproteinase Arg-C 7. 5 - 8. 5 C-terminal to R Endoproteinase Asp-N 7 N-terminal to D, C, E Endoproteinase Glu-C in phosphate 4. 0 -8. 0 C-terminal to E, D Endoproteinase Glu-C in ammonium bicarbonate 4. 0 -8. 0 C-terminal to E Endoproteinase Lys-C 8. 5 -8. 8 C-terminal to K, N Pepsin 2. 0 -4. 0 C-terminal to F, L and E Trypsin 7~9 C-terminal to K, R (除了KP, RP)
Protein Are Bulit From A Repertoire of 20 Amnio Acids
The L and D Isomers of Amino Acids Mirror-image forms Alpha-amnio acids are chiral.
Only L amino acids are Constituents of Proteins For almost all amino acids, the L isomer has S absolute configuration
Ionization State as a Function of p. H
Structures of Gly and Ala
Amino Acids with Aliphatic Side Chains
Clyclic Structure of Proline
Amino Acids with Aromatic Side Chains
Absorption of Spectra of Aromatic Amino Acids Tryptophan and Tyrosine
Amino Acids Containing Aliphatic Hydroxyl Groups
Structure of Cysteine Disulfide bond
Basic Amino Acids
Positively Charged at Neutral p. H
Histidine Ionization Histidine can bind or release protons near physiological p. H Histidine is often found in the active sites of enzymes, where the imidazole ring can bind and release protons in the course enzymatic reactions
Amino Acids with Sidechain Carboxylates and Carboxamides • Asp and Glu are negatively charged at physiological p. H
Seven of 20 Amino Acids have Readily Ionizable Side Chains • These 7 amino acids are able to donate or accept protons to facilitate reactions as well as to form ionic bonds
Abbreviations for Amino Acids
微生物應用 業 Ch 5. 微生物催化劑 阮雪芬 Nov 19, 2002 NTUT www. ntut. edu. tw/~yukijuan/lectures/Microbio/Nov 19. ppt
Primary Structure
Peptide-bond Formation
Amino Acid Sequences Have Direction
Components of a Polypeptide Chain • Backbone: constant • Side chains: variable
Cross-links Disulfide bond
Amino Acid Sequence of Bovine Insulin
Peptide Bond Are Plane Side chain AA 1 AA 2
• C-N single bond: 1. 49 • C=N double bond: 1. 27
Secondary Structure
Structure of Alpha Helix
Schematic Views of alpha helices Ball-and-stick Ribbon Cyclindrical
Structure of a Beta Strand An antiparallel beta sheet A parallel beta sheet
Structure of a Mixed Beta Sheet
A Twisted beta Sheet
A Protein Rich in Beta Sheets The structure of a fatty acid-binding proteins
Structure of a Reverse Turn H bond Reverse turn is also known as the beta turn or hairpin bend
Loops on a Proteins Surface Unlike alpha helices and beta strands, loops do not have regular, periodic structure
Tertiary Structure
Three-dimensional Structure of Myoglobin The first protein to been seen in atomic detail.
Distribution of Amino Acids in Myoglobin : Hydrophobic amino acids : Charged amino acids : others
Protein Domains The cell-surface protein CD 4 consists of four similar domains
Quaternary Structure
Dimer The Cro Protein of Bacteriophage Lamda
Tetramer
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