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CENTRAL CARBON → BRANCHED-CHAIN AMINO ACIDS → INDIVIDUAL PATHWAY

Valine biosynthesis

Follow the carbon skeleton from 2 Pyruvate to L-Valine.

What it needs

Pyruvate, reducing power and an amino-group donor.

What it supplies

L-Valine. 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.

Valine biosynthesis2 Pyruvate to 2-Acetolactate via Acetolactate synthase (IlvB/IlvN); 2-Acetolactate to 2,3-Dihydroxy-3-methylbutanoate via Ketol-acid reductoisomerase (IlvC); 2,3-Dihydroxy-3-methylbutanoate to 2-Oxoisovalerate via Dihydroxy-acid dehydratase (IlvD); 2-Oxoisovalerate to L-Valine via Branched-chain amino-acid aminotransferase (IlvE)2 Pyruvate1. Acetolactate synthase (IlvB/IlvN)CO₂ released; thiamine-diphosphate-dependentRead reaction 12-Acetolactate2. Ketol-acid reductoisomerase (IlvC)NADPH → NADP⁺Read reaction 22,3-Dihydroxy-3-methylbutanoate3. Dihydroxy-acid dehydratase (IlvD)Water released; Fe–S enzymeRead reaction 32-Oxoisovalerate4. Branched-chain amino-acid aminotransferase (IlvE)Glutamate → 2-oxoglutarate; PLP-dependentRead reaction 4L-Valine

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Reactions and enzymes

1 · Acetolactate synthase (IlvB/IlvN)

2 Pyruvate → 2-Acetolactate

Acetolactate synthase (IlvB/IlvN) · EC 2.2.1.6

Inputs, helpers or coproducts: CO₂ released; thiamine-diphosphate-dependent

2 · Ketol-acid reductoisomerase (IlvC)

2-Acetolactate → 2,3-Dihydroxy-3-methylbutanoate

Ketol-acid reductoisomerase (IlvC) · EC 1.1.1.86

Inputs, helpers or coproducts: NADPH → NADP⁺

3 · Dihydroxy-acid dehydratase (IlvD)

2,3-Dihydroxy-3-methylbutanoate → 2-Oxoisovalerate

Dihydroxy-acid dehydratase (IlvD) · EC 4.2.1.9

Inputs, helpers or coproducts: Water released; Fe–S enzyme

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

2-Oxoisovalerate → L-Valine

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

Inputs, helpers or coproducts: Glutamate → 2-oxoglutarate; PLP-dependent

Connected pathways

Evidence and scope

The 2-oxoisovalerate intermediate also feeds the leucine branch. Enzyme-subunit organization varies. 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.

Compare the related Aquifex annotation group →