Glycolysis Regulation: Key Enzymes and Inhibitors

Study Notes

Glycolysis Regulation

Phosphofructokinase-1 (PFK-1) is a key regulatory enzyme in glycolysis.
PFK-1 is activated by AMP and fructose-2,6-bisphosphate, and inhibited by ATP and citrate.
PFK-1 controls the rate-limiting step of glycolysis, converting fructose-6-phosphate to fructose-1,6-bisphosphate.

Hexokinase Regulation

Hexokinase catalyzes the first step of glycolysis, phosphorylating glucose to glucose-6-phosphate.
Hexokinase is inhibited by glucose-6-phosphate, regulating the entry of glucose into the glycolytic pathway.

Lactate Production and Accumulation

During intense exercise, pyruvate is converted into lactate through lactate fermentation.
Lactate fermentation helps regenerate NAD+ for continued glycolysis and energy production.
Lactate is a valuable energy source for muscles and other tissues.
Accumulation of lactate in the bloodstream leads to increased blood lactate levels, an indicator of metabolic stress during exercise.

Oxidative Aerobic System

The oxidative aerobic system, also known as aerobic metabolism or oxidative phosphorylation, produces energy through the breakdown of carbohydrates, fats, and proteins in the presence of oxygen.
This process occurs mainly in the mitochondria during low to moderate-intensity activities.
Pyruvate generated from glycolysis undergoes further breakdown in the mitochondria through the Krebs cycle and electron transport chain to produce ATP.

Glucose and Glycogen Oxidation

Glucose oxidation involves the breakdown of glucose molecules to produce ATP through glycolysis and oxidative phosphorylation.
Glucose is converted into pyruvate in the cytoplasm, producing a small amount of ATP and NADH.
If oxygen is available, pyruvate enters the mitochondria for further oxidation, generating a large amount of ATP through oxidative phosphorylation.
Glycogen is a storage form of glucose found in the liver and muscles.
Glycogenolysis is the process by which glycogen is broken down into glucose molecules to supply energy during periods of high energy demand.
Glucose molecules released from glycogen undergo the same metabolic pathways as exogenous glucose, ultimately producing ATP.

Description

Learn about the crucial regulation of glycolysis, including the key enzymes phosphofructokinase-1 and hexokinase, and their activators and inhibitors. Understand how these regulatory points ensure efficient energy production in cells.