Synthesis and use of isotope-labelled substrates for a mechanistic study on human α-methylacyl-CoA racemase 1A (AMACR; P504S)
作者:Daniel J. Darley、Danica S. Butler、Samuel J. Prideaux、Thomas W. Thornton、Abigail D. Wilson、Timothy J. Woodman、Michael D. Threadgill、Matthew D. Lloyd
DOI:10.1039/b815396e
日期:——
α-Methylacyl-CoA racemase (AMACR) is an important enzyme for the metabolism of branched-chain lipids and drugs. The enzyme is over-expressed in prostate and other cancers. AMACR 1A, the major splice variant, was purified from recombinant E. colicells as a His-tag protein. Purified enzyme catalysed chiral inversion of both S- and R-2-methyldecanoyl-CoA, with an equilibrium constant of 1.09 ± 0.14 (2S/2R). Reactions with 2H-labelled substrate showed that loss of the α-proton was a prerequisite for chiral inversion. Reactions conducted in 2H2O indicated that reprotonation was not stereospecific. These results are the first mechanistic study on any recombinant mammalian α-methylacyl-CoA racemase.
Unexpected stereoselective exchange of straight-chain fatty acyl-CoA α-protons by human α-methylacyl-CoA racemase 1A (P504S)
作者:Fouzia A. Sattar、Daniel J. Darley、Francesco Politano、Timothy J. Woodman、Michael D. Threadgill、Matthew D. Lloyd
DOI:10.1039/c002509g
日期:——
α-Methylacyl-CoA racemase (AMACR; P504S) catalysed exchange of straight-chain fatty acyl-CoA α-protons. One α-proton was removed in each catalytic cycle, with the pro-S proton preferred. This reaction was most efficient for straight-chain substrates with longer side-chains. 2-Methyldecanoyl-CoA underwent α-proton exchange 3à more efficiently (as judged by Kcat/Km) than decanoyl-CoA.