title: Inhibition of carnitine acetyltransferase by mildronate, a regulator of energy metabolism.
abstract: Carnitine acetyltransferase (CrAT; EC 2.3.1.7) catalyzes the reversible transfer of acetyl groups between acetyl-coenzyme A (acetyl-CoA) and L-carnitine; it also regulates the cellular pool of CoA and the availability of activated acetyl groups. In this study, biochemical measurements, saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy, and molecular docking were applied to give insights into the CrAT binding of a synthetic inhibitor, the cardioprotective drug mildronate (3-(2,2,2-trimethylhydrazinium)-propionate). The obtained results show that mildronate inhibits CrAT in a competitive manner through binding to the carnitine binding site, not the acetyl-CoA binding site. The bound conformation of mildronate closely resembles that of carnitine except for the orientation of the trimethylammonium group, which in the mildronate molecule is exposed to the solvent. The dissociation constant of the mildronate CrAT complex is approximately 0.1 mM, and the K(i) is 1.6 mM. The results suggest that the cardioprotective effect of mildronate might be partially mediated by CrAT inhibition and concomitant regulation of cellular energy metabolism pathways.
authors.affiliation: Latvian Institute of Organic Synthesis, Riga, Latvia.
authors.forename: Kristaps
authors.initials: K
authors.lastname: Jaudzems
authors.forename: Janis
authors.initials: J
authors.lastname: Kuka
authors.forename: Aleksandrs
authors.initials: A
authors.lastname: Gutsaits
authors.forename: Kirils
authors.initials: K
authors.lastname: Zinovjevs
authors.forename: Ivars
authors.initials: I
authors.lastname: Kalvinsh
authors.forename: Edgars
authors.initials: E
authors.lastname: Liepinsh
authors.forename: Edvards
authors.initials: E
authors.lastname: Liepinsh
authors.forename: Maija
authors.initials: M
authors.lastname: Dambrova
mesh_terms: D000818:Animals; D001665:Binding Sites; D055162:Biocatalysis; D002317:Cardiovascular Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D002332:Carnitine O-Acetyltransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D010856:Columbidae; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008763:Methylhydrazines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D056004:Molecular Dynamics Simulation; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D002317:Cardiovascular Agents; D004791:Enzyme Inhibitors; D008763:Methylhydrazines; C050147:3-(2,2,2-trimethylhydrazine)propionate; D002332:Carnitine O-Acetyltransferase