© 2008 W. H. Freeman and Company

CHAPTER 20Carbohydrate Biosynthesis in Plants and Bacteria

식물과세균의탄수화물생합성

1.Dark rx of photosynthesis 광합성의탄수화물합성

2. Photorespiration and the C4 and CAM plant광호흡과 C4 및 CAM 경로

3. Biosynthesis of starch, sucrose녹말과설탕의생합성

4. Cell wall (cellulose, peptidoglycan)세포벽합성: 식물의셀룰로스와세균의펩티도글리칸

5. Integration of carbohydrate metabolism in plant식물세포에서탄수화물대사의통합

CO2 Assimilation (CO2 fixation or carbon fixation) in plant이산화탄소동화(고정), 탄소고정(conversion of CO2 to reduced

organic cpd)이산화탄소를환원된유기물로의

전환

1. 광합성에의한탄수화물합성

CO2 Assimilation 이산화탄소고정

=Calvin cycle캘빈회로=photosynthetic carbon

reduction cycle 광합성탄소환원회로

The origin and interconversion of Plastids

색소체의기원과상호전환(plant organelle for biosynthesis)

Amyloplast 아밀로플라스트(chloroplast w/o

pigments, thylakoids)

amyloplast

3 stages of CO2 Assimilation광합성생물에서의이산화탄소동화의 3단계 (화학양론)

(carbon fixation, reduction of CO2 to GA3P/DHP, regeneration of RubP)탄소고정, 이산화탄소의 GA3P/DHP로의환원, RubP의재생

3 인산글리세르산

ribulose 1,5 bisphosphate carboxylase oxygenase(rubisco)1,5-이중인산리불로스카복실화효소산화효소(루비스코)의구조

8L8S (550 kd), 엽록체 stromaform I, vascular plant 유관속식물, algae조류, cyanobacteria 남조류low turnover 낮은활성도 (3 CO2/sec), high concentration 높은농도 (250mg/ml)

ribulose 1,5 bisphosphate (C5)+ CO2 → C6→ 2 3-phosphoglycerate(C3)how? 1945 Malvern CO2 Chlorella (unicellular green algae)

어떻게? 1945, 멜번, 동위원소표지이산화탄소, 클로렐라

central role of Mg+2 in catalysis of rubisco루비스코의촉매는마그네슘이온이중요

Rubisco form II

in photosynthetic bacteria

광합성박테리아

이산화탄소 동화의 1단계; 루비스코의 카복실화효소 활성

이산화탄소 동화의 1단계; 루비스코의 카복실화효소 활성

1,5 이인산 리불로스가 활성자리에 엔디올산을 형성

Mg+2의접근으로극성을 띤이산화탄소는엔디올산에의해 친핵공격을 당해 가지달린6탄소 당을 생성

C-3 카보닐에서수산화 일어남

절단후 한 분자의3 인산글리세르산을형성

탄소음이온(carbanion)이양성화되어두번째3인산글리세르산을생성

rubisco activase 루비스코활성화효소some spp activated by light 일부종에서는빛으로활성화

효소의리신201이변형되지않고1,5 이중인산리불로스가결합되어있으면루비스코는불활성화상태

1,5 이인산리불로스를 ATP 사용해제거함으로 Lys201의아미노기가노출

아미노기는이산화탄소에의해카바모일화됨. 마그네슘이카바모일 Lys에결합하여루비스코를활성화함.

nocturnal inhibitor 야행성억제제natural TS analog for β keto acid베타케토산전이구조체구조유사체synthesized in dark어둠에서생성broken down w/ light or expelled by rubisco activase빛에의해분해또는루비스코활성효소에의해축출

2nd stage ; reduction requiring 2ATP/ 2NADP for 3 phosphoglycerate into glyceraldehyde 3-pi이단계; 3 인산글리세르산을 2ATP와 2NADPH2를사용하여글리세르알데히드 3 인산으로환원

글리세르알데히드 3 인산3단계로 RuDP로재생

일부, 녹말, 서당또는해당작용으로사용

3rd stage, 3단계-reductive pentose phosphate cycle인산삼탄당으로부터인산 1,5이인산리불로스의재생

C3 x 5 = C5 x 3

Synthesis of carbohydrate

Aldolase 알돌라제 1,4 반응Transketolase 트랜스케톨라제3,6 반응Blue steps;2,5,9 rxs; exergonic, irreversible비가역적반응

transketolase reaction in Calvin cycle캘빈회로의트랜스케톨라제촉매반응

TPP cofactor; carrier of two carbon

rich in outer layer of rice

polished ricecausing beriberi(pain in lime, muscle weakness distorted skin sensation)

*pyruvate dehydrogenase complex

Regeneration of ribulose 1,5 bisphosphate 1,5 이인산리불로스의재생

stoichiometry of CO2 assimilation in Cavin cycle캘빈회로에서이산화탄소동화의화학량론

Pi triose phosphate antiport 엽록체내막의인산삼탄당역수송계Inner Chl memAlso for transporting of 3 phosphoglycerate/ ATP

CO2 Fixation

Reduction

Recovery ofreactant

C5

C1C3

C3COCLUSION

Pi trios phosphate antiporter (one kind) in transporting ATP and reducing equivalents

Role of the Pi triose phosphate antiporter in the transport of ATP and reducing equivalentsATP와환원당량의수송에서 Pi-인산삼탄당역수송체의역할

Several Enzymes of dark rx are indirectly activated by light암반응의여러효소는빛에의해간접적으로활성화됨.

pH and [Mg+2] increase in stroma as a result of light rx

1. Rubiscofaster formation of

carbamoyllysine at high pH and active Mg active site at high [Mg]

2. Activation of chloroplast fructose 1,6 bisphosphatase (FBPase 1) activated by light , pH, Mg

높은 pH, Mg+2, light는엽록체 1,6 이중인산과당인산염분해효소의활성화

3. Light activation of several enzymes of the Calvin cycle캘빈회로의 4효소의빛에의한활성화

sedoheptulose 1,7 bisphosphatae, fructose 1,6 bisphosphatase, rubulose 5 phosphate kinase, G 3P dehydrogenase

Reduced form of enzymes are active.

activation

inactivation

2. Photorespiration and the C4 and CAM pathway광호흡, C4, CAM회로

Oxygenase activity of rubisco루비스코의산소화효소활성

lncorporating O2 rather than CO2 into RubPRubP에이산화탄소대신산소를붙임.

at 1/3~1/4 rate at the same active site이반응은 ¼ 속도로일어남

Km for CO2, ~9uM; for O2, 350uMIn solution [CO2]=11uM, [O2]=250uM

Oxygenase activity of rubisco

Photorespiration(oxidative photosynthetic carbon cycle or C2 cycle)광호흡(산화적광합성탄소회로또는 C2 회로)

by Oxygenase activity of rubisco+ glyoxylate pathway

vs. mitochondrial respiration

Glycolate pathway글리콜산경로

2 phosphoglycolateto glycolate

4C (glycolate, 글리콜산) to C3 (ser, 세린) + CO2, NH4

O2 consumed, CO2 released

ATP consumedNADPH syn

Glycine decarboxylase system글리신탈카복실기효소계

~PDH or αKDH

P, +PLPH, lipoic acidT, tetrahydrofolateL, FAD

N5, N10 methylene H4 folate + Gly to form SerBy Ser hydroxymethyltransferase

Net reaction2 glycine + NAD+ + H2OSerine + CO2 + NH3 + NADH + H+

C4 plant(Hatch Slack pathway)

rubisco- higher oxygenase activity at high tempin tropical plant

엽육세포

플라스모데스마타

유관속초세포

C4 plant

유관속초세포

엽육세포

인산엔올피루브산카복실화효소

C4 plant

CAM plant (CAM식물)(crassulacean acid metabolism)eg) catus, pineapple

in dark, stomata is open.CO2 is fixed into malate and stored in vacuoles

어둠에서기공이열려스트로마에서이산화탄소를 말산으로고정하여보관

In light, stomata is closed, minimizing water loss,malate is converted into CO2 and malate.

빛이있을때기공닫혀수분의손실을최소하면서, 말산으로부터이산화탄소를 배출

Carbon fixation Carbon assimilation

C3 plant - Mesophyll cell

Cytosol : PEPC X

Chloroplast : rubisco O

C4 plant

Mesophyll cell

Cytosol : PEPC X Bundle sheath cell

Cytosol : PEPC X

Chloroplast : rubisco O

Chloroplast : rubisco O

CAM plantMesophyll cell –cytosol : PEPC O Mesophyll cell – chloroplast : rubisco

O

PEPC :phosphoenol pyruvate carboxylase

In daylight

In night In daylight

글리세르알데히드 3 인산3단계로 RuDP로재생

일부, 녹말, 서당또는해당작용으로사용

3. Synthesis of sugar and starch synthesis

sucrose synthesis 설탕

6인산서당생성효소

6인산서당인산염분해효소

UDP포도당 6인산과당

starch synthesis

two site insertion mechanism

Fructose 2,6 bisPi as regulator of sucrose synthesis설탕합성의조절자로서의2, 6 이중인산과당

regulation of sucrose phosphate synthase by phosphorylation

Regulation of ADP glucose phosphorylase

cellulose

cellulose synthesis

peptidoglycan structure

bacterial peptidoglycan

5. conversion of stored fatty acids to sucrose in germinating seeds

식물세포에서탄수화물대사의통합

conversion of stored fatty acid to sucrose

conversion of glycerol moiety of triacylglycerols to sucrose in germinating seeds

발아종자에서트리글리세롤의글리세롤부분이설탕으로의전환

Pools of hexose phosphate, pentose phosphates, and triose phosphates

인산오탄당,인산삼탄당,인산육탄당등의풀

The Pi–triose phosphate antiport system of the inner chloroplast membrane

For sucrose biosynthesis

For photophosphoryla