Trp279 is involved in the binding of quaternary ammonium at the peripheral site of Torpedo marmorata acetylcholinesterase.
Specific photoaffinity labelling of purified acetylcholinesterase from Torpedo marmorata by p-N,N-[3H]dimethylamino benzenediazonium and p-N,N-[3H]dibutylamino benzenediazonium derivatives was demonstrated. This occurred at the active site of the enzyme for lower concentrations of the probes and at the peripheral ammonium binding site for higher concentrations. The affinities and the rate constants of alkylation for each probe on both sites have been established. Specific labelling at the peripheral site of the enzyme with both probes allowed the identification of radio-labelled peptides having the common sequence K270PQELIDVEW. The radioactivity was always associated with the residue Trp279 indicating the preferential ammonium complexation with this aromatic residue.
Schalk
I
I
Laboratoire de Chimie Bio-organique, URA 1386 CNRS, Université Louis Pasteur Strasbourg, Faculté de Phamacie, France.
Ehret-Sabatier
L
L
Bouet
F
F
Goeldner
M
M
Hirth
C
C
D000110:Acetylcholinesterase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D000345:Affinity Labels; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D003979:Diazonium Compounds / Q000378:metabolism*; D004557:Electric Organ / Q000201:enzymology*; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010449:Peptide Mapping; D014101:Torpedo; D014357:Trypsin; D014364:Tryptophan
D000345:Affinity Labels; D003979:Diazonium Compounds; D010446:Peptide Fragments; D014364:Tryptophan; D000110:Acetylcholinesterase; D014357:Trypsin