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Flashcards in glycolysis flash Deck (21)
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Glycolysis 1st regulated step

Hexokinase (inhibited by G6P)(low Km for glucose)/ Glucokinase (liver and pancreas)(under low BGL, GK in sequestered in nucleus). Trap glucose as G6P in cell

3

Glycolysis 2nd regulated step

Phosphofructokinase-1. Major regulated step, sugar commited to glycolytic pathway. Inhibitors: ATP and citrate. Activators: F2,6 BP (links glycolysis to hormonal regulation) and AMP

4

Glyceraldehyde-3P DH

Enzyme requires sulfhydral group from Cys. Generates NADH

5

Glycolysis 3rd regulated step

Pyruvate kinase. PEP-->Pyruvate + ATP. 3 forms of PK (L: liver, M1/M2: muscle/other, R: RBC)

6

Cardiac PFK-2

Phosphorylated by insulin-stimulated PKB or AMP-activated PK, when phosphorylated its kinase activity is active (opposite of lver PFK2). Allows heart glycolysis to be active under low energy conditions or when glucose is high (insulin release)

7

Liver Pyruvate kinase

Activate: High PEP or F 1,6 BP. Inhibit: high ATP, alanine, covalent modification by cAMP dep. PKA (phosphorylation)

8

PKA

c-AMP dependent Protein Kinase A. Glucagon/ epinephrine activates adenyl cyclase ATP--> c-AMP. Then PKA R2C2 + c-AMP--> R-cAMP + C. Then "C" causes phosphorylation and inactivation of PFK-2 and PK in liver. Liver then exports glucose and makes gluco via gluconeogenesis.

9

Cori Cycle

Muscle forms lactate to regenerate NAD+ to continue glycolysis. Carbons form lactate reach liver and help make glucose which is exported via blood to muscle.

10

Fructokinase

Very active in converting Fructose to F1P. Require ATP. IV fructose load causes rapid P depletion

11

Amylose

Major form of carbohydrate, comes from starch. Repeating glu alpha(1,4) glu

12

Amylopectin

Starch also. Alpha (1,4) and alpha (1,6)

13

Lactose

gal beta (1,4) glu

14

Sucrose

glu alpha (1,2) fru

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Endoglycosidase

cleaves alpha (1,4). From salivary amylase. Creates dextrins

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cellulose

glu beta (1,4) glu. No human enzymes to hydrolyze

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Pyruvate carboxylase

Enzyme to reverse glycolysis. Pyruvate + ATP + CO2 + Biotin --> OAA. Mitochondria. Activated by acetyl-CoA

18

PEP Carboxykinase

Enzyme to reverse glycolysis. OAA + GTP --> CO2 + GDP + PEP. Cyto.

19

Fructose 1,6 Bisphosphatase

Enzyme to reverse glycolysis. F1,6BP --> F6P + P. Cyto. Activate: ATP/ citrate. Inhibit: F2,6 BP/ AMP (reverse of PFK1)

20

G6 Phosphatase

Enzyme to reverse glycolysis. G6P--> Glucose + P. Only in liver and kidney. Cyto.

21

Pyruvate DH

Inhibited by acetyl-CoA