해당과정(glycolysis), 효소 정리, rate limiting step

해당과정(glycolysis), rate limiting step, 효소 정리

glycolysis, 해당과정, 효소와 rate limiting step 등 총정리

 

-glycolysis <-> glyconeogenesis

배부를때    / 배고플때

 

-glycolysis : 해당과정,

-하나의 glucose가 한번 해당과정을 돌면 2개의 ATP를 사용하고 4개의 ATP를 생산, 총 2개 ATP가 생성된다.

 

-총 3개의 irreversible step, rate limiting step이 존재.

-반응에서 사용된 효소는 (효소)로 표기

-따로 표기하지 않으면 다 reversible step이다.

---

 

glucose

->

(hexokinase, glucokinase)

(ATP -> ADP, ATP사용step)

(irreversible, rate limiting step)

->

glucose 6- phosphate

->

(phosphoglucose isomerase)

<-

furctose 6 - phosphate

->

(PFK1 , phosphofructokinase -1)

(ATP -> ADP, ATP사용step)

(irreversible, rate limiting step)

->

fructose 1,6 biphosphate

->

(aldorase)

<-

glyceraldehyde 3-phosphate , dehydroxylacetone phosphate(DHAP)

->

(둘 간에 triose phosphate isomerase로 전환 가능,

DHAP가 glyceraldehyde 3 - phosphate로 전환해 총 G3P 2분자가 나온다.)

<-

glyceraldehyde 3-phosphate (X2)

->

(glyceraldehyde 3-phosphate dehydrogenase)

(NAD+ -> NADH, H+)

<-

1,3 Bisphosphoglycerate

->

(phophoglycerate kinase)

(ADP -> ATP, ATP 생산 step) : 2ATP생산

<-

3 - phosphoglycerate

->

(phosphoglycerate mutase)

<-

2 - phosphoglycerate

->

(enolase)

<-

phosphoenolpyruvate

->

(PK, pyruvate kinase)

(ADP -> ATP, ATP 생산 step) : 2ATP생산

(irreversible, rate limiting step)

->

pyruvate

->

(aerobic condition)

(NADH,H+ -> NAD+)

<-

lactate

 

---

 

효소 다 생략하고 물질만 쭉 써보면 아래와 같다.

glucose -> glucose 6-phosphate -> fuctose 6-phosphate -> fructose 1,6 bisphosphate -> glyceraldehyde 3-phophate, DHAP, -> 1,3 bisphosphoglycerate -> 3-phophoglycerate -> 2-phosphoglycerate ->phosphoenolpyruvate -> pyruvate (->lactate)

 

 

---

Rate - limiting step  (irreversible reaction)

 

1. glucose -> glucose 6-phosphate

 

-관여효소는 hexokinase, glucokinase

-반응시 1ATP사용

 

-GK조절은 indirectly by fructose 6 phosphate, glucose, transcriptionally by insulin

-insulin 많으면 촉진된다.

 

---

 

2. fructose 6- phosphate -> fructose 1, 6 bisphosphate

 

관여효소는 PFK1, phosphofructokinase-1

반응시 1ATP사용

 

-촉진은 AMP, F2,6BP, insulin, PFK-2 kinase(F2,6BP증가시킴)

-억제는 ATP, citrate, glucagon, PFK-2 phosphatase(F2,6BP감소시킴)

 

참고로 insulin은 PFK-2를 탈인산화시켜 F2,6BP를 증가시켜 glycolysis증가

glucagon은 PFK-2를 인산화시켜 F2,6BP를 감소시켜 glycolysis 감소

 

F2,6BP는 fructose 2,6 bisphosphate임.

 

---

 

3. phosphoenolpyruvate -> pyruvate

-관여효소는 PK(pyruvate kinase)

-반응시 2 ATP 생성

 

-PK 조절은

-촉진 : PFK-1 활성화 ~ F1,6BP증가시 PK활성화 (feedforward), insulin

-억제 : glucagon -> cAMP증가(by adenylyl cyclase) -> PKA활성화 -> PK인산화, 불활성화 (

간에서의 covalent regulation)

 

 

---

ATP 사용하는 반응 

: glucose -> glucose 6 phosphate

fructose 6 phosphate -> fructose 1,6 bisphosphate

 

---

 

ATP 생산하는 반응(=기질수준인산화)

: 1,3 bisphosphoglycerate -> 3 phosphoglycerate

phosphoenolpyruvate -> pyruvate

 

1 해당과정(glycolysis) => 총 2개의 ATP생성!

 

 

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일단 끝!!!!!!

 

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