CENTRAL CARBON → BRANCHED-CHAIN AMINO ACIDS → INDIVIDUAL PATHWAY

Leucine biosynthesis

Follow the carbon skeleton from 2-Oxoisovalerate + acetyl-CoA to L-Leucine.

What it needs

2-Oxoisovalerate from the valine precursor route, acetyl-CoA, NAD⁺ and an amino-group donor.

What it supplies

L-Leucine. This product can enter downstream cellular reactions; its synthesis depends on the precursor and helper supplies shown.

The pathway

Read from top to bottom. Select an enzyme box to jump to its reaction. Cosubstrates and selected coproducts appear in the account below.

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Reactions and enzymes

1 · 2-Isopropylmalate synthase (LeuA)

2-Oxoisovalerate + acetyl-CoA → 2-Isopropylmalate

2-Isopropylmalate synthase (LeuA) · EC 2.3.3.13

2 · Isopropylmalate isomerase (LeuC/LeuD)

2-Isopropylmalate → 3-Isopropylmalate

Isopropylmalate isomerase (LeuC/LeuD) · EC 4.2.1.33

Inputs, helpers or coproducts: Dehydration / rehydration via isopropylmaleate

3 · 3-Isopropylmalate dehydrogenase (LeuB)

3-Isopropylmalate → 2-Oxoisocaproate

3-Isopropylmalate dehydrogenase (LeuB) · EC 1.1.1.85

Inputs, helpers or coproducts: NAD⁺ → NADH; CO₂ released

4 · Branched-chain amino-acid aminotransferase (IlvE)

2-Oxoisocaproate → L-Leucine

Branched-chain amino-acid aminotransferase (IlvE) · EC 2.6.1.42

Inputs, helpers or coproducts: Glutamate supplies the amino group

Connected pathways

Valine biosynthesis Isoleucine biosynthesis

Evidence and scope

The dedicated leucine branch extends the ketoacid carbon skeleton before final transamination. This page explains selected documented biochemical reactions. It does not establish that every displayed enzyme occurs in Aquifex, that the pathway is universally essential, or that the book image records a complete organism. Gene symbols name common enzyme activities; organism-specific protein records require separate matching.

Original explanatory diagram and reaction account, based on the records below. Arrows show the biosynthetic reading direction; they do not claim that every reaction is irreversible. Selected protons, water and cofactors are omitted from the overview and are not implied absent.