Acetylcholinesterase and acetylcholine receptor. Final report, 1 April 1992-30 September 1995
1 Bromo-214Cpinacolone (34CbrPin) inactivates AcChEs, from T. nobiliana labeling Cys 231, and E. electricus labeling His-440, and possibly Trp-435 and Asn-533. 14Cphenacyl bromide, (14CphABr) inactivates, labeling Cys-231 and His-550 in T. nobiliana, and His-550 in E. electricus. Five sequenced peptides in T. nobiliana, are identical with those from T. califomica. Four peptides from E. electricus show 77 - 96% homology. Inactivations by BrPin or PhABr exclude 3Hdfp; inactivation by DFP does not exclude 14CbrPin or 14CphABr. In studies with 14CbrPin, 5-trimethylammonio-2-pentanone was the preferred protecting agent; with 14CphABr, 3-trimethylammonioacetophenone was used with T. nobiliana, phenyltrimethylammonium ion with E. electricus. N-Methylacridinium protects E. electricus against PhABr, but accelerates inactivation of T. nobiliana. Acetylcholine protects E. electricus against PhABr, indicating that His-550 marks the site at which the binding of high concentration of the substrate inhibits its own hydrolysis, possibly important in its action as a neurotransmitter. Photolysis of pivalophenone leading to benzoyl and tert-butyl radicals, inactivates the enzymes. Protection is offered by radical scavenging thiols.
- Research Organization:
- Brandeis Univ., Waltham, MA (United States)
- OSTI ID:
- 273186
- Report Number(s):
- AD-A-307113/1/XAB; CNN: Contract DAMD17-92-C-2070; TRN: 62121231
- Resource Relation:
- Other Information: PBD: Oct 1995
- Country of Publication:
- United States
- Language:
- English
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