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Literature summary extracted from

  • Kim, J.; Darley, D.; Buckel, W.
    2-Hydroxyisocaproyl-CoA dehydratase and its activator from Clostridium difficile (2005), FEBS J., 272, 550-561.
    View publication on PubMed

Activating Compound

EC Number Activating Compound Comment Organism Structure
4.2.1.157 activator HadI the homodimeric activator is extremely oxygen-sensitive. Recombinant HadI activates the dehydratase in the presence of ATP, MgCl2 and a one-electron reducing agent titanium(III) citrate or dithionite Clostridioides difficile

Cloned(Commentary)

EC Number Cloned (Comment) Organism
4.2.1.157 the hadBC and hadI genes from Clostridium difficile are functionally expressed in Escherichia coli. They encode the 2-hydroxyisocaproyl-CoA dehydratase HadBC and its activator HadI Clostridioides difficile

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
4.2.1.157 0.05 0.08 (R)-2-hydroxy-4-methylpentanoyl-CoA pH 8.0, temperature not specified in the publication Clostridioides difficile

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
4.2.1.157 Iron the enzyme contains 5.7 nonheme iron and 6.1 acid-labile sulfur, determined by chemical analysis Clostridioides difficile
4.2.1.157 Zn2+ besides varying amounts of zinc, other metal ions, particularly molybdenum, are not detected in the dehydratase Clostridioides difficile

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
4.2.1.157 42350
-
 1 * 46578 + 1 * 42350, calculated from sequence Clostridioides difficile
4.2.1.157 43000
-
 2 * 43000, SDS-PAGE Clostridioides difficile
4.2.1.157 46578
-
 1 * 46578 + 1 * 42350, calculated from sequence Clostridioides difficile
4.2.1.157 90000
-
 gel filtration Clostridioides difficile

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
4.2.1.157 (R)-2-hydroxy-4-methylpentanoyl-CoA Clostridioides difficile i.e. (R)-2-hydroxyisocaproyl-CoA. The enzyme is involved in the reductive branch of L-leucine fermentation 4-methylpent-2-enoyl-CoA + H2O i.e. isocaprenoyl-CoA ?

Organism

EC Number Organism UniProt Comment Textmining
4.2.1.157 Clostridioides difficile Q5U923 and Q5U924 hadC: Q5U923, hadB: Q5U924
-

Purification (Commentary)

EC Number Purification (Comment) Organism
4.2.1.157
-
 Clostridioides difficile

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
4.2.1.157 (R)-2-hydroxy-4-methylpentanoyl-CoA i.e. (R)-2-hydroxyisocaproyl-CoA. The enzyme is involved in the reductive branch of L-leucine fermentation Clostridioides difficile 4-methylpent-2-enoyl-CoA + H2O i.e. isocaprenoyl-CoA ?
4.2.1.157 (R)-2-hydroxy-4-methylpentanoyl-CoA i.e. (R)-2-hydroxyisocaproyl-CoA. The enzyme is specific for the R-isomer. The reduced activator transfers one electron to the dehydratase concomitant with hydrolysis of ATP. The activated dehydratase is separated from the activator and ATP. It catalyzes about 10000 dehydration turnovers until the enzyme becomes inactive. Adding activator, ATP, MgCl2, dithionite and dithioerythritol reactivates the enzyme. The enzymatic elimination of H2O probably occurs in syn-fashion. In assays using (E)-isocaprenoyl-CoA as substrate, no activity can be observed suggesting that the dehydration is irreversible under these conditions or the Z-isomer is the correct product Clostridioides difficile 4-methylpent-2-enoyl-CoA + H2O i.e. isocaprenoyl-CoA ?

Subunits

EC Number Subunits Comment Organism
4.2.1.157 heterodimer 2 * 43000, SDS-PAGE Clostridioides difficile
4.2.1.157 heterodimer 1 * 46578 + 1 * 42350, calculated from sequence Clostridioides difficile

Synonyms

EC Number Synonyms Comment Organism
4.2.1.157 2-hydroxyisocaproyl-CoA dehydratase
-
 Clostridioides difficile
4.2.1.157 HadBC
-
 Clostridioides difficile

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
4.2.1.157 8
-
 assay at Clostridioides difficile

General Information

EC Number General Information Comment Organism
4.2.1.157 metabolism the enzyme is involved in L-leucine fermentation Clostridioides difficile