Enzyme - Enoyl-[acyl-carrier-protein] reductase (NADPH, Si-specific)

Alternative Name(s)
  • Enoyl acyl-carrier-protein reductase.
  • Acyl-ACP dehydrogenase.
  • Enoyl-ACP reductase.
  • NADPH 2-enoyl Co A reductase.

Catalytic Activity

No Catalytic Activity was found for this Enzyme


There are no Cofactors for this Enzyme

Reaction Mechanism

    2-enoyl thioester reductases catalyse the reduction of trans-2-enoyl acyl carrier protein/coenzyme A to acyl carrier protein/coenzyme A. Yeast enzymes, such as Etr1p and Mrf1p, are responsible for the NADPH dependent reaction in mitochondrial fatty acid synthesis, and are indispensible for respiratory function in yeast. They belong to the medium chain dehydrogenases/reductases (MDR) superfamily and are structurally distinguishable from the prokaryotic 2-enoyl thioester which belong to the short chain dehydrogenases/reductases (SDR) superfamily. The Candida tropicalis genes ETR1 and ETR2 both encode enzymatically active 2-enoyl thioester reductases, which can form both homodimers and heterodimers.

    The proposed mechanism is based on analogy with the prokaryotic enoyl thioester reductases such as InhA. A hydride is transferred from NADPH to the beta position of the alpha-beta unsaturated carbonyl substrate (Michael addition) to give an enol(ate) intermediate. The hydroxy group of Tyr 79 acts as an electrophilic catalyst by forming a hydrogen bond to the substrate carbonyl to stabilise the intermediate and the transition state leading to it.
    Catalytic Residues
    AA Uniprot Uniprot Resid PDB PDB Resid
    Tyr Q8WZM3 79 1guf 57
    Step Components

    overall reactant used, overall product formed, proton transfer, intermediate formation, aromatic unimolecular elimination by the conjugate base, cofactor used, intermediate collapse, hydride transfer, michael addition

    Step 1.

    Tyr79 acts as an electrophilic catalyst by hydrogen bonding to the carbonyl group of alpha-beta unsaturated carbonyl substrate. A hydride is transferred from NADPH to the beta-position in a conjugate addition reaction, forming an intermediate enolate and NADP.

    Step 2.

    The enolate intermediate collapses and the substrate is protonated at the alpha-carbon, forming the reduced product.


    The products of the reaction.

Reaction Parameters

There are no kinetic parameters information for this Enzyme

Associated Proteins

Protein name Organism
Putative dehydrogenases Staphylococcus aureus
Enoyl-acyl carrier protein reductase III Brochothrix thermosphacta
Flagellin modification protein A Escherichia coli
Enoyl-(Acyl-carrier-protein) reductase (NADPH) FabL Rhodococcus sp. AD45
Putative enoyl-[acyl-carrier-protein] reductase (NADPH, B-specific) Pseudomonas putida (strain ATCC 47054 / DSM 6125 / NCIMB 11950 / KT2440)