Proceso de Glucólisis y Enzimas Involucradas

Glycolysis Process and Enzymes Involved

Glycolysis is a fundamental metabolic pathway in which glucose is converted into pyruvate through ten enzymatic steps, yielding two pyruvate molecules and producing energy in the form of ATP and NADH. The process is divided into two phases: the priming phase and the payoff phase.

Glycolysis Process

Priming Phase

1. Glucose phosphorylation: The first step involves the phosphorylation of glucose to form glucose-6-phosphate (G6P) by the enzyme hexokinase. This reaction is rate-limiting and requires the input of energy in the form of ATP.

2. Isomerization: The isomerization of glucose-6-phosphate to fructose-6-phosphate (F6P) is catalyzed by phosphoglucoisomerase.

3. Phosphorylation: Fructose-6-phosphate is then phosphorylated at the 1 carbon position to form fructose-1,6-bisphosphate (F1,6BP) by the enzyme phosphofructokinase-1 (PFK-1). This is the committed step of glycolysis, as it has a large ΔG value.

4. Aldol cleavage: Fructose-1,6-bisphosphate is cleaved into two three-carbon molecules, dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P), by the enzyme fructose bisphosphate aldolase.

Payoff Phase

1. Phosphorylation: Glyceraldehyde-3-phosphate is phosphorylated at the 3 carbon position to form 3-phosphoglyceraldehyde (3PGA) by the enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

2. Phosphorylation and dephosphorylation: 3-phosphoglyceraldehyde is then phosphorylated to form 1,3-bisphosphoglycerate (1,3BPG) by the enzyme triose phosphate isomerase (TIM). The 1,3-bisphosphoglycerate is then dephosphorylated to form 2-phosphoglycerate (2PG) by the enzyme aldolase.

3. Phosphorylation: 2-phosphoglycerate is phosphorylated at the 3 carbon position to form 3-phosphoglycerate (3PG) by the enzyme phosphoglycerate kinase (PGK).

4. Phosphorylation: 3-phosphoglycerate is phosphorylated at the 2 carbon position to form 2-phosphoglycerate by the enzyme phosphoglyceromutase (PGM).

5. Decarboxylation: The final step involves the decarboxylation of 2-phosphoglycerate to form pyruvate and carbon dioxide (CO2) by the enzyme enolpyruvylshikimate-3-phosphate synthase (EPSPS).

Enzymes Involved

The enzymes involved in glycolysis include:

1. Hexokinase: Converts glucose to glucose-6-phosphate.

2. Phosphoglucoisomerase: Catalyzes the isomerization of glucose-6-phosphate to fructose-6-phosphate.

3. Phosphofructokinase-1: Phosphorylates fructose-6-phosphate to fructose-1,6-bisphosphate.

4. Fructose bisphosphate aldolase: Cleaves fructose-1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.

5. Glyceraldehyde-3-phosphate dehydrogenase: Phosphorylates glyceraldehyde-3-phosphate to 3-phosphoglyceraldehyde.

6. Triose phosphate isomerase: Converts 3-phosphoglyceraldehyde to 3-phosphoglycerate.

7. Phosphoglycerate kinase: Phosphorylates 3-phosphoglycerate to 1,3-bisphosphoglycerate.

8. Phosphoglyceromutase: Converts 1,3-bisphosphoglycerate to 2-phosphoglycerate.

9. Enolpyruvylshikimate-3-phosphate synthase: Decarboxylates 2-phosphoglycerate to form pyruvate and carbon dioxide.