Accession Number : ADP008831

Title :   Labeling by 1-bromo-2-14C-Pinacolone of His-440 and Trp-435 in Acetylcholinesterase from Electrophorous Electricus.

Corporate Author : BRANDEIS UNIV WALTHAM MA DEPT OF CHEMISTRY

Personal Author(s) : Salih, Erdjan ; Chisti, S. B. ; Vicedomine, Patrick ; Cohen, Saul G. ; Chiara, David C.

Report Date : 13 MAY 1993

Pagination or Media Count : 9

Abstract : Acetylcholinesterase (AcChE), isolated from electric organ of E. electricus, was characterized by SDS-PAGE, titration with 7-(dimethylcarbamoyloxy)-N-methylquinolinium and hydrolysis of AcCh and AcSCh. Peptide labeled by 3(H)dfp was isolated and sequenced from Gln-193 to Arg-216, with label at Ser-200, 83% homologous with that deduced for T. californica, with Gln-193, Ala-203, Leu-210, and Asp-214 in place of thr, Gly, Ile and Gly, respectively. (3H)DFP labeled peptide of T. nobiliana AcChE was identical to that of T. californica. Inactivation of AcChE from E. electricus by 1-bromo-2-(14C)pinacolone (14C)BrPin) led to two labeled peptides sequenced from Ala-427 to Leu-450, identical to that deduced for T. californica, one with 14C release indicating label at active-site His-440, protected by 5-trimethylammonio-2-pentanone (TAP), the other, not protected by TAP, with label apparently at Trp-435. Label was also found at two extra-active-site residues where alkylation may lead to decreased activity. In contract, (14C)BrPin inactivates and labels AcChE from T. nobiliana by reaction with Cys-231, a residue not present in E. electricus. With both AcChEs inactivation by BrPin prevents reaction with (3H)DFP, and prior inactivation by DFP does not prevent reaction with (14C)BrPin.

Descriptors :   *ACETYLCHOLINESTERASE, *HYDROLYSIS, ALKYLATION, ALUMINUM ARSENIDES, INACTIVATION, LABELS, PENTANONES, PEPTIDES, RESIDUES, TITRATION, EELS.

Subject Categories : Biochemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE