Links between Metabolic Pathways of Carbohydrates, Lipids, Amino Acids, and Nucleotides
Central Role of Glucose:
- Glycolysis: Glucose is converted to pyruvate, yielding ATP and NADH.
- Gluconeogenesis: Synthesis of glucose from non-carbohydrate precursors like lactate, amino acids, and glycerol.
Links between Metabolic Pathways of Carbohydrates, Lipids, Amino Acids, and Nucleotides
Interconnection through Acetyl-CoA:
- Carbohydrates: Pyruvate from glycolysis is converted to acetyl-CoA.
- Lipids: Fatty acid β-oxidation produces acetyl-CoA.
- Amino Acids: Some amino acids are deaminated and converted into acetyl-CoA or other TCA cycle intermediates.
- Nucleotides: Pentose phosphate pathway provides ribose-5-phosphate for nucleotide synthesis and NADPH for fatty acid synthesis.
Links between Metabolic Pathways of Carbohydrates, Lipids, Amino Acids, and Nucleotides
Tricarboxylic Acid (TCA) Cycle:
- Central hub integrating carbohydrates, fats, and proteins.
- Provides intermediates for biosynthetic processes (e.g., α-ketoglutarate and oxaloacetate for amino acid synthesis).
Role of Common Metabolites and Key Enzymes
ATP and NADH/NADPH:
- Universal energy carriers, used in various biosynthetic and energy-consuming pathways.
- NADPH specifically used in biosynthesis (e.g., fatty acid synthesis).
Role of Common Metabolites and Key Enzymes
Acetyl-CoA:
- Key metabolic intermediate linking carbohydrate, lipid, and protein metabolism.
- Precursor for TCA cycle, fatty acid synthesis, and cholesterol synthesis.
Role of Common Metabolites and Key Enzymes
Enzymes:
- Hexokinase/Glucokinase: Phosphorylation of glucose to glucose-6-phosphate.
- Phosphofructokinase-1 (PFK-1): Regulates glycolysis; activated by AMP, inhibited by ATP and citrate.
- Pyruvate Dehydrogenase Complex: Converts pyruvate to acetyl-CoA; regulated by phosphorylation.
- Fatty Acid Synthase: Catalyzes the synthesis of fatty acids from acetyl-CoA and malonyl-CoA.
- Glucose-6-Phosphate Dehydrogenase: Key enzyme in the pentose phosphate pathway, producing NADPH.