TY - JOUR
T1 - Inactivation of Electrophorus electricus acetylcholinesterase by benzenemethane sulfonylfluoride
AU - Barnett, Philip
AU - Rosenberry, Terrone L.
N1 - Funding Information:
This investigation was supported, in part, by the National Science Foundation Grant PCM73-00744 and by the New York Heart Association, Inc.
PY - 1978/9
Y1 - 1978/9
N2 - Benzenemethane Sulfonylfluoride (329-98-6) is an irreversible inactivator of many esterases including mammalian acetylcholinesterases. However, previous reports indicated that acetylcholinesterase from the electric eel, Electrophorus electricus (EC 3.1.1.7) failed to react with benzenemethane sulfonylfluoride at measurable rates. We report here that eel acetylcholinesterase reacts with this inactivator at a low rate. Hydrolysis of the sulfonylating agent is so much faster than enzyme inactivation that, under most conditions, there will be only slight inactivation. Like the reaction of other active site acylating agents with this enzyme, inactivation can be accelerated in the presence of certain organic cations. We introduce a rate equation for enzyme sulfonylation which incorporates both the hydrolysis of the inactivator and the complication that fluoride resulting from hydrolysis of the inactivator is a potent competitive inhibitor of this enzyme. This rate equation accurately describes the time course of enzyme inactivation.
AB - Benzenemethane Sulfonylfluoride (329-98-6) is an irreversible inactivator of many esterases including mammalian acetylcholinesterases. However, previous reports indicated that acetylcholinesterase from the electric eel, Electrophorus electricus (EC 3.1.1.7) failed to react with benzenemethane sulfonylfluoride at measurable rates. We report here that eel acetylcholinesterase reacts with this inactivator at a low rate. Hydrolysis of the sulfonylating agent is so much faster than enzyme inactivation that, under most conditions, there will be only slight inactivation. Like the reaction of other active site acylating agents with this enzyme, inactivation can be accelerated in the presence of certain organic cations. We introduce a rate equation for enzyme sulfonylation which incorporates both the hydrolysis of the inactivator and the complication that fluoride resulting from hydrolysis of the inactivator is a potent competitive inhibitor of this enzyme. This rate equation accurately describes the time course of enzyme inactivation.
UR - http://www.scopus.com/inward/record.url?scp=0018178559&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0018178559&partnerID=8YFLogxK
U2 - 10.1016/0003-9861(78)90268-0
DO - 10.1016/0003-9861(78)90268-0
M3 - Article
C2 - 708070
AN - SCOPUS:0018178559
SN - 0003-9861
VL - 190
SP - 202
EP - 205
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -