Ch 15: Glycolysis

Question 0

Hk, mechanism

Answer 0

Hexokinase, step 1. Glucose to g6p; confo change brings p group to spot on glucose and excludes water

Question 1

Describe substrates, prods, enz mechanisms for step 1 of glycolysis

Answer 1

1: OH group on 6’ C gets P, hexokinase Mg2+. Prod: glucose 6 phosphate.

Question 2

G6p

Answer 2

Glucose 6 phosphate, made in step 1

Question 3

Glucokinase

Answer 3

Hk isozyme in liver that maintains blood glucose levels

Question 4

F6p

Answer 4

Fructose 6 phosphate, made in step 2 by pgi phosphoglucose isomerase

Question 5

Pgi

Answer 5

Phosphoglucose isomerase; enz for step 2; g6p to f6p; enzymatic acid on enz opens ring, base removes proton and ring closes

Question 6

Pfk

Answer 6

Phosphofructokinase 3; rate determining; enhanced allos by amp and inh by atp & others; yields FBP

Question 7

Aldol cleavage, mech and step?

Answer 7

1. FBP carbonyl

Question 8

Glu 165 His 95

Answer 8

Act as gen acids/bases. Glu Takes c2 proton from gap acid. his protonates carbonyl oxygen base. Step 5 tim

Question 9

Tim

Answer 9

Triose phosphate isomerase. Flexible loop on enz prevents toxic methylglyoxal from forming. Step 5, cat perfect: allows for gap to form quickly to maintain equilibrium

Question 10

Gapdh

Answer 10

Glyceraldehyde3phosphate dehydrogenase. Rxn 6. H from c1 of gap goes to nad+. Isotope exchange heavy p to pi= sim to ser protease rxn.

Question 11

Pgk

Answer 11

Step 7. Sim to hexokinase. Phosphoglycerate kinase. Rxn coupled to prev gapdh rxn. Pulls bisphospho’tion rxn forward. Sub lvl phos’tion

Question 12

Pgm

Answer 12

Phosphoglycerate mutase. Step 8. His 8 rxs w 3PG, both spots are pho’ted, then removed from spot 3

Question 13

Enolase

Answer 13

Dehydrates 2pg to pep. F inh

Question 14

Pk

Answer 14

Pyruvate kinase, rxn 10. Pep cleavage is coupled w atp synth. Tautomerizes to keto form> pyruvate (taut is very exothermic)