mr. october

"the straw that stirs the drink." reggie jackson, the former yankee slugger, is known for his postseason heroics, in particular his 3-homers-on-3-pitches world series game (i forget which year). he was the prototypical playoff catalyst, and it is in his honor that i write this last-minute entry on key biochemical enzymes.

in glycolysis, there are four irreversible regulated steps:

D-glucose --> glucose-6-phosphate
- glucokinase in liver, hexokinase everywhere else

fructose-6-phosphate --> fructose-1,6-bisphosphate
- phosphofructokinase (rate-limiting step)
- inhibited by ATP, citrate
- stimulated by AMP, fructose-2,6-bisphosphate

phosphoenolpyruvate --> pyruvate
- pyruvate kinase
- inhibited by ATP, alanine
- stimulated by fructose-1,6-bisphosphate

pyruvate --> acetyl-CoA
- pyruvate dehydrogenase complex
- inhibited by ATP, NADH, acetyl-CoA

the common theme regarding glycolytic enzyme regulation is that high energy molecules or molecules produced by high energy processes inhibit glycolysis, i.e. telling the glycolytic pathway that it no longer needs to metabolize glucose to make energy.

in the citric acid cycle, here are the key regulated enzymes:

citrate synthase
- inhibited by ATP

isocitrate dehydrogenase
- rate-limiting step
- inhibited by ATP, NADH
- promoted by ADP

alpha-ketoglutarate dehydrogenase
- inhibited by succinyl-CoA, ATP, NADH

like glycolysis, the TCA cycle is slowed by those molecules signalling adequate energetic fuel.

bah. i'm pretty sure a lot of what i just wrote is incorrect. sleepy time.