國立台灣大學生物資源暨農業學院 植物光生態生理學 (plant photo-ecophysiology)...

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國立台灣大學生物資源暨農業學院

植物光生態生理學(Plant Photo-ecophysiology)

第 7 章 ATP 的合成

楊棋明 博士

中央研究院植物研究所暨生物多樣性研究中心Email: cmyang@gate.sinica.edu.tw

Tel: 02-27821258#612, 613

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Four stages of photosynthesis in higher plants

Stage 1: absorption of light

Chl Chl*2H2O O2 ＋ 4H ＋＋ 4e －

Stage 2: electron transport and generation of a proton-motive force (pmf)/pH gradient

2H2O ＋ 2NADP ＋ 2H ＋＋ 2NADPH＋ O2

Stage 3: synthesis of ATP

ADP3 －＋ Pi2 － ATP4 －

Stage 4: carbon fixation

6CO2 ＋ 18ATP4 －＋ 12NADPH ＋ 12H2OC6H2O ＋ 18ADP3 －＋ 18Pi2 －＋ 12NADP ＋＋ 6H ＋

light

light

light

Thyla

koid

m

embr

ane

Stro

ma

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Chemical structure of ATP, ADP and AMP and their energy

ATP ＋ H2O ADP ＋ Pi ＋ 7.3kcal/molADP ＋ H2O AMP ＋ Pi ＋ 7.3kcal/molAMP ＋ H2O Adenosine ＋ Pi ＋ 3.4kcal/mol

7.3kcal/mol 7.3kcal/mol 3.4kcal/mol

ATPADP AMP Adenosine

Ribo

se

Adenine

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ATP synthesis in chloroplast (1): the chemiosmotic hypothesis

Pete Mitchell (UK) in 1961 proposed a chemiosmotic hypothesis to account for ATP formation accompanying electron transport in mitochondria and chloroplasts.Pete Mitchell was awarded the Nobel Prize in 1978.Paul Boyer (USA) and John Walker (UK), elucidating the ATPase structure and function, were awarded the Nobel Prize in 1997.

The Chemiosmotic Hypothesis:

Intact membranes are almost impermeable to the passive flow of protons.The electron donors and acceptors of electron and proton are arranged vectorially in the membrane.During photosynthetic electron transport, protons are translocated from the external medium (stroma) into the osmotic space of the intra-thylakoid membrane.

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ATP synthesis in chloroplast (2): the chemiosmotic hypothesis

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ATP synthesis in chloroplast (3): ATPase or ATP synthase/ coupling factors/ CF0CF1 complex

Paul Boyer (USA) and John Walker (UK), elucidating the ATPase structure and function, were awarded the Nobel Prize in 1997.

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Inside-out and outside-in of mitochondrial and chloroplast

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Construction of artificial ATP synthesis system

lumen

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ATP synthesis (4): bacteria, mitochondria, chloroplast

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Comparison of chemiosmosis in mitochondria and chloroplasts

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Subunits and their structures of ATPase complex in eukaryotes

(α3β3γδε)

C, chloroplastN, nucleus

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ATPase in the bacteria, mitochondria, chloroplast

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Rotational model for ATP synthesis

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Experimental evidence for rotation of ATPase

ATPase is a rotatory motor.

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Mitochondrial ATPase

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Structure and location of ATPase on the thylakoid membrane

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Have you a nice day