Regulation of Glycolysis

Flashcards on Regulation of Glycolysis

Hexokinase

Catalyzes the irreversible conversion of glucose to glucose 6-phosphate (G6P).

Phosphofructokinase-1 (PFK-1)

Catalyzes the irreversible phosphorylation of fructose 6-phosphate (F6P) to fructose 1,6-phosphate (F1,6-P).

Pyruvate Kinase

Catalyzes the irreversible conversion of phosphoenolpyruvate (PEP) to pyruvate.

Phosphoglycerate Kinase

Catalyzes the conversion of 1,3-bisphosphoglycerate (1,3-BPG) to 3-phosphoglycerate (3-PG), yielding 2 ATP per glucose.

Glyceraldehyde 3-phosphate dehydrogenase

Catalyzes the conversion of glyceraldehyde 3-phosphate dehydrogenase, yielding 2 NADH per glucose.

Allosteric site

Site other than the active site which can control the overall three-dimensional shape of the enzyme, resulting in activation or inhibition.

Insulin

Released from pancreatic beta cells when glucose levels are high; activates hexokinase and glucokinase, stimulating glycolysis and inhibiting gluconeogenesis.

Glucagon

Released from pancreatic alpha cells when glucose levels are low; inhibits hexokinase and glucokinase, stimulating glycolysis and inhibiting gluconeogenesis.

Citrate

Krebs Cycle intermediate; ↑ citrate = ↑ Krebs cycle activity = ↑ NADH, FADH2 = ↑ ATP = ↑ energy supply

Fructose 2,6-bisphosphate (F2,6-BP)

Most powerful regulator of PFK-1. When its concentration decreases, it also stimulates fructose 1,6-bisphosphatase which eventually converts that to glucose.

Adenosine diphosphate (ADP)

ATP is broken down into ADP and inorganic phosphate by hydrolysis.

Phosphofructokinase-2 (PFK-2) / Fructose 2,6-bisphosphatase (F2,6-BPase)

An enzyme complex with two different types of domains that can be allosterically and hormonally regulated.

Feed forward reaction

Metabolite produced early in the pathway activates an enzyme that catalyze a reaction further down the pathway.

Long-Chain Fatty Acyl CoA (LCFA)

Undergoes beta oxidation producing acetyl CoA.

Arsenate

Competes with organic phosphate as a substrate for G3-PDH, forming a complex that spontaneously hydrolyzes to form 3-phosphoglycerate, bypassing the synthesis of and phosphate transfer from 1,3-BPG.