Ch.16

Glycolysis

-occurs in the cytosol
-ten enzyme catalyzed rxns divided into 2 stages
-occur primarily in muscles and brain
-stage 2 yields gross 4ATP and 2 NADH (net ATP 2)
-2 pyruvates oxidatively decarboxylated & form 2 acetyl CoA to enter Citric Acid Cycle

Hexokinase (glucokinase) requires...

ATP and Mg2+

Hexokinase (glucokinase) is inhibited by...

G6P

Phosphohexose Isomerase

-catalyzes the isomerization of an aldose to a ketose
-rate determining step of glycolysis
-allosterically regulated

What makes PFK have a higher affinity for F6P?

F2,6BP

What type of mechanism does aldolase have?

covalent catalysis

What is the "perfect enzyme" and why?

Triose Phosphate Isomerase b/c P forms as rapidly as ES forms

Important step b/c it generates a compound with high phosphoryl transfer

GAP Dehydrogenase

3 major stages of catabolism

1) large molecules broken down
2) small molec. processed into Acetyl CoA
3) ATP produced from the ox. of the acetyl component

GAP Dehydrogenase

-produces NADH (yield 2.5 ATP in ox. phosphorylation)
-phosphoryl transfer as weel as redox

What is the mechanism used or GAP Dehydrogenase?

covalent catalysis

What does PGK (phosphoglycerate kinase) require?

Mg2+

An example of substrate level phosphorylation.

Phosphoglycerate kinase PGK

What does enolase require?

Mg2+

eliminates H2O to form an alkene

enolase

second site for ATP production pyruvate kinase

phosphoenolpyruvate

mechanism involves a nu- attack by an oxygen in ADP on the phosphate on PEP

pyruvate kinase

allosterically regulated by AMP; 1,6 Bisphosphate and inhibited by ATP, acetyl CoA, and alanine

pyruvate kinase

in yeast pyruvate is converted into

ethanol