Acetylcholine receptor: Modification of synaptic gating mechanism after treatment with a disulfide bond reducing agent

1975 ◽  
Vol 355 (1) ◽  
pp. 19-26 ◽  
Author(s):  
D. Ben-Haim ◽  
F. Dreyer ◽  
K. Peper
Keyword(s):  
Acetylcholine Receptor ◽  
Disulfide Bond ◽  
Reducing Agent ◽  
Gating Mechanism

scholarly journals Chemical Modification of the Active Site of the Acetylcholine Receptor

1969 ◽  
Vol 54 (1) ◽  
pp. 245-264 ◽  
Author(s):  
Arthur Karlin
Keyword(s):  
Chemical Modification ◽  
Acetylcholine Receptor ◽  
Disulfide Bond ◽  
Active Site ◽  
Quaternary Ammonium ◽  
Competitive Inhibitor ◽  
Affinity Labels ◽  
Electrophorus Electricus ◽  
Depolarizing Agents ◽  
Monoquaternary Ammonium

The receptor for acetylcholine in the subsynaptic membrane of the electroplax of Electrophorus electricus is a protein with a disulfide bond in the vicinity of the active site. This disulfide can be reduced and reoxidized with concomitant inhibition and restoration of the response to acetylcholine and other monoquaternary ammonium-depolarizing agents. Conversely, the bisquaternary hexamethonium, normally a competitive inhibitor, causes depolarization, and the activity of decamethonium is increased following reduction of the disulfide. The reduced receptor can be alkylated by various maleimide derivatives and is then no longer reoxidizable. Some quaternary ammonium maleimide derivatives act as affinity labels of the reduced receptor, alkylating it at a rate three orders of magnitude faster then do uncharged maleimide derivatives. Other types of potential affinity labels also react only with the reduced receptor and the resulting covalently attached quaternary ammonium moieties interact with the active site, strongly activating the receptor. These results suggest a model for the active site and its transitions in which an activator such as acetylcholine bridges between a negative subsite and a hydrophobic subsite in the vicinity of the disulfide, causing an altered conformation around the negative subsite and a decrasee of a few angstroms in the distance between the two subsites.

scholarly journals Free thiol groups are essential for infectivity of human cytomegalovirus

1999 ◽  
Vol 80 (11) ◽  
pp. 2861-2865 ◽  
Author(s):  
Ali Mirazimi ◽  
Mehrdad Mousavi-Jazi ◽  
Vivi-Anne Sundqvist ◽  
Lennart Svensson
Keyword(s):  
Human Cytomegalovirus ◽  
Disulfide Bond ◽  
Virus Entry ◽  
Bond Formation ◽  
Reducing Agent ◽  
Disulfide Bond Formation ◽  
Thiol Groups ◽  
Nitrobenzoic Acid ◽  
Free Thiol

The membrane-impermeable thiol blocker 5′5-dithiobis 2- nitrobenzoic acid (DTNB) blocked infectivity of human cytomegalovirus (CMV) although the virus still bound to cells. DTNB-treated CMV regained 65% of its infectivity after incubation with the disulfide bond-reducing agent dithiothreitol. These observations suggest that free thiol groups on CMV are required for infectivity and may participate in disulfide bond formation during virus entry.

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