title: The effect of the experimental antitumor agent caracemide on brain choline acetyltransferase.
abstract: Caracemide was found to inhibit choline acetyltransferase (CAT) from rat brain. A concentration of 0.5 mM caracemide inhibited the enzyme by 93%, whereas a degradation product from caracemide, N-(methylcarbamoyloxy)acetamide, produced only a 50% inhibition. Two other degradation products, N-(methyl-carbamoyloxy)-N'-methylurea and N-hydroxy-N'-methylurea, lacked any inhibitory activity. With bovine brain CAT, caracemide showed noncompetitive inhibition with the substrate choline, Km 337 microM, Ki240 microM, Vmax 2.83 nmol acetylcholine formed/min/mg protein and mixed inhibition with the substrate acetyl-CoA, Km 21 microM, Ki 146 microM, Vmax 3.85 nmol acetylcholine formed/min/mg protein.
authors.affiliation: Department of Neuro-Oncology, U.T.M.D. Anderson Hospital, Houston 77030.
authors.forename: B T
authors.initials: BT
authors.lastname: Ho
authors.forename: L W
authors.initials: LW
authors.lastname: Tansey
authors.forename: R
authors.initials: R
authors.lastname: Feiffer
authors.forename: R A
authors.initials: RA
authors.lastname: Newman
authors.forename: D
authors.initials: D
authors.lastname: Farquhar
authors.forename: W S
authors.initials: WS
authors.lastname: Fields
authors.forename: I H
authors.initials: IH
authors.lastname: Krakoff
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001921:Brain / Q000201:enzymology*; D002795:Choline O-Acetyltransferase / Q000037:antagonists & inhibitors*; D006918:Hydroxyurea / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats
chemical_list: D000970:Antineoplastic Agents; D002795:Choline O-Acetyltransferase; C044466:caracemide; D006918:Hydroxyurea