Metabolic Flux in E.coli

Catabolic reactions

• Catabolic reactions are the breakdown of large molecules into smaller ones, liberating energy.
• In metabolism, these are generally incentivised by ATP production.
• Glycolysis
• Krebs cycle
• Pentose phosphate pathway

Glycolysis

• There are 2 phases in glycolysis: priming and substrate level phosphorylation.
• The overall reaction is:
• glucose + 2 ADP + 2 Pi + 2 NAD --> 2 pyruvate + 2 ATP + 2 NADH + 2H

Substrate level phosphorylation

• A phosphate from one reactive metabolic intermediate of higher phosphate energy than ATP (31.8 KJ/mol) donates to an ADP under the facility of a kinase enzyme.

Functions of the p. phosphate pathway

• There are 2 major functions of the pp pathway: generation of precursor metabolites, and generation of reducing power in the for NADPH.
• 30% of glucose-6-phosphate is diverted from glycolysis to the PP pathway. Once the precursor metabolite concentration is met, the surplus erythrose-4-phosphate is shunted back into glycolysis as fructose-6-phosphate.
• 2 NADPH are formed during oxidative decarboxylation of glucose-6-phosphate to ribulose-5-phosphate.