微生物應用工業微生物應用工業Ch5. Ch5. 微生物催化劑微生物催化劑

微生物應用工業微生物應用工業Ch5. Ch5. 微生物催化劑微生物催化劑

阮雪芬阮雪芬Oct 29, 2002Oct 29, 2002

NTUTNTUT

www.ntut.edu.tw/~yukijuan/lectures/Microbio/Oct29.ppt

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

– 金屬離子– 輔酵素 : Holoenzyme = Apoenzyme + Coenzym– 輔基質 (Cosubstrate): NAD+, NADP+, ATP, CoA

多為維生素

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)

酵素之物理化學性質• 酵素活性化能

– Arrhenius equation: E= 2.303R log (Kr2/Kr1)/(1/T1-1/T2)

• 酵素反應動力學– 單純酵素反應

E + S E – S E + P dc/dt = k +2 (e-c)S-k-1C-k+2C

K+1

K-1

酵素之物理化學性質 - 酵素反應動力學

• 單純酵素反應– Lineweaver-Burk 1/v = Km/V·1/S + 1/V

• 複雜酵素反應

常用酵素之性質與用途 - 加水分解酵素

• 配糖體加水分解酵素 (glycoside hydrase), 又稱為碳水化合物分解酵素 (Carbohydrase)

• 蛋白質分解酵素 (Protease) 又稱 peptide hydrase

• Endo-peptidase• Exo-peptidase

• 酯分解酵素

常用酵素之性質與用途– 蛋白質分解酵素 (Protease) 又稱 peptide h

ydrase• Endo-peptidase

– Trypsin– Chymotrypsin

• Exo-peptidase– Carboxypeptidase– Leucine aminopeptidase

酵素與切割位置 名稱 最佳 pH 值 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)

常用酵素之性質與用途 - 氧化還原酵素

• 脫氫酵素與還原酵素• 氧化酵素• 催化酵素與過氧化酵素• 加氧酵素

常用酵素之性質與用途 - 轉移酵素

• A + B -X A-X + B

常用酵素之性質與用途 - 分解酵素 (Lyase)

常用酵素之性質與用途 - 異構酵素 (Isomerase or Mutase)

• D- 葡萄糖 D- 果糖

常用酵素之性質與用途 - 合成酵素 (Ligase)

常用酵素之性質與用途 - 凝固酵素

• 牛奶凝固酵素• 凝血酵素

常用酵素之性質與用途 - 其他酵素

Protein Are Bulit From A Repertoire of 20 Amnio Acids

The L and D Isomers of Amino Acids

Alpha-amnio acids are chiral.

Mirror-image forms

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 pH

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 Tyros

ine

Amino Acids Containing Aliphatic Hydroxyl Groups

Structure of Cysteine

Disulfide bond

Basic Amino Acids

Positively Charged at Neutral pH

Histidine Ionization

Histidine can bind or release protons near physiological pHHistidine 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 Side-chain Carboxylates and Carboxa

mides•Asp and Glu are negatively charged at physiological pH

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