Mutation of Tyr375 to Lys375 allows medium-chain acyl-CoA dehydrogenase to acquire acyl-CoA oxidase activity

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

6 Scopus Citations
View graph of relations


  • Jia Zeng
  • Yuandong Liu
  • Long Wu
  • Ding Li


Original languageEnglish
Pages (from-to)1628-1634
Journal / PublicationBiochimica et Biophysica Acta - Proteins and Proteomics
Issue number12
Publication statusPublished - Dec 2007


Medium-chain acyl-CoA dehydrogenase (MCAD) and acyl-CoA oxidase (ACO) are key enzymes catalyzing the rate-determining step for the β-oxidation of fatty acids. Tyr375 of MCAD is conserved in all acyl-CoA dehydrogenases and is an important residue for substrate binding. Four Tyr375 variant enzymes of rat liver MCAD were obtained through site-directed mutagenesis. Y375K was found to have intrinsic acyl-CoA oxidase activity, which was confirmed using HPLC analysis, while the wild-type and other Tyr375 variant enzymes did not show detectable oxidase activity. The kinetic parameters for the oxidase activity of Y375K variant enzyme were determined to be kcat of 320 ± 80 h- 1 and KM of 30 ± 15 μM using hexanoyl-CoA as the substrate. The oxidase activity of Y375K increased more than 200 times compared with that reported for the MCAD wild-type enzyme from mammalian sources. Molecular modeling study shows that the solvent accessible area for Y375K variant enzyme is wider than that of the wild-type enzyme, which indicates that Tyr375 may function as a switch against solvent accession. The mutation of this residue to Lys375 allows molecular oxygen to enter into the catalytic site serving as the electron acceptor for the reduced FAD cofactor. © 2007 Elsevier B.V. All rights reserved.

Research Area(s)

  • β-Oxidation, Acyl-CoA dehydrogenase, Acyl-CoA oxidase, Fatty acid, Solvent accessible area

Citation Format(s)