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生 物 氧 化. Biological Oxidation. contents. Introduction Respiratory chain oxidative phosphorylation. I. Introduction. 1. Definition.
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生 物 氧 化 Biological Oxidation
contents • Introduction • Respiratory chain • oxidative phosphorylation
I. Introduction 1. Definition Biological oxidation is the process in which substances (carbohydrates, fats, amino acids) are oxidized in living organism and the energy of oxidation drives the synthesis of ATP.
2. characteristic • mild reaction condition • Forming of H2O • Forming of CO2 • Produce of energy
II. Respiratory chain • Definition of Respiratory chain A chain in the mitochondria consists of a number of redox carriers for transferring hydrogens removed from the substrate to oxygen to form water. The chain is termed a respiratory chain, also called electron transport chain (ETC).
5. constituents of Respiratory Chain (1). Nicotinamide coenzymes (烟酰胺核苷酸) • NAD+/NADH (Nicotinamide Adenine Dinucleotide, CoⅠ) • NADP+/NADPH(Nicotinamide Adenine Dinucleotide Phosphate, CoⅡ)
(2). Flavin prosthetic groups (黄素辅基) • FMN: FlavinMononucleotide • FAD: Flavin Adenine Dinucleotide They contain the riboflavin (Vit B2).
(3) Fe-S (铁硫蛋白) Iron-sulfur centers (Iron-sulfur protein,Fe-S) are prosthetic groups containing 2, 3, 4 or 8 nonheme iron atoms complexed to elemental and cysteine S.
(4). CoQ Coenzyme Q (CoQ, ubiquinone) is very hydrophobic. It dissolves in the membrane. Coenzyme Q functions as a mobile e- carrier within the mitochondrial inner membrane.
(5). Cytochromes Cytochromes (Cyt)are proteins with heme prosthetic groups. They absorb light at characteristic wavelengths.
Heme b Heme a Heme c • Hemes in the 3 classes of cytochrome (a, b, c) differ slightly in substituents on the porphyrin ring system.
The heme iron can undergo an electron transition between ferric and ferrous states: Fe3+ + e- Fe2+
2Fe2+-S NADH+H+ Q FMN NAD+ FMNH2 2Fe3+-S QH2 ComplexⅠ NADH→ →CoQ FMN; Fe-SN-1a,b;Fe-SN-4;Fe-SN-3; Fe-SN-2
2Fe2+-S 琥珀酸 Q FAD 延胡索酸 FADH2 2Fe3+-S QH2 ComplexⅡ 琥珀酸→ →CoQ Fe-S1;b560;FAD;Fe-S2 ;Fe-S3
Complex Ⅲ QH2→ →Cyt c b562; b566; Fe-S; c1
Complex Ⅳ 还原型Cyt c → → O2 CuA→a→a3→CuB
7. Two main Respiratory Chains NADH Chain 1 Q C Q C 4 4 3 3 2 FADH2 Chain
Ⅲ. Oxidative phosphorylation Ways of ATP produce: Oxidative phosphorylation Substrate level phosphorylation
Oxidative phosphorylation: The phosphorylation of ADP to ATP coupled to electron transfer from a substrate to molecular oxygen. Substrate level phosphorylation: Phosphorylation of ADP or GDP to ATP or GTP coupled to the dehydrogenation of an organic substrate.
The synthesis of per molecule ATP require 4 molecules of H+ pumped back to matrix used up per ATP). 3 3
3 ~P bonds synthesized during oxidation of NADH produced in the matrix. • 2 ~P bonds synthesized during oxidation of FADH2 produced in the matrix.