On the Kinetics of Inhibition of rat-brain Acetylcholine esterase by Sevin

The inhibition of rat-brain acetylcholinesterase with Sevin was shown to be partly reversible. The rate of progression of the irreversible inhibition is extremely slow and follows the kinetics of a unimolecular reaction, with Κ=3.65 · 10-3 min-1 and t 0.5 190 minutes. The reversible inhibition of the enzyme was found to be of competitive nature. The dissociation constant of E — I (Ki) was determined —by two different methods —to be 5.7 and 7.6 · 10-6 Μ. The presence of acetylcholine protects the enzyme against the irreversible attack of Sevin. It is believed that acetylcholine esterase does not participate in the biological degradation of Sevin in the nervous tissue.

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Kinetics of inhibition of rat brain acetylcholinesterase by 3-diethylaminophenyl-N-methyl- and -N-phenylcarbamate methoiodide in vitro

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19761959 ◽

1976 ◽

Vol 41 (7) ◽

pp. 1959-1964

Author(s):

J. Patočka ◽

J. Bajgar

Keyword(s):

Rat Brain ◽

Kinetics Of ◽

Kinetics Of Inhibition ◽

Brain Acetylcholinesterase

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Inhibition of hen brain acetylcholinesterase and neurotoxic esterase by chlorpyrifos in vivo and kinetics of inhibition by chlorpyrifos oxon in vitro: Application to assessment of neuropathic risk*

Fundamental and Applied Toxicology ◽

10.1006/faat.1993.1036 ◽

1993 ◽

Vol 20 (3) ◽

pp. 273-279 ◽

Cited By ~ 29

Author(s):

R RICHARDSON ◽

T MOORE ◽

U KAYYALI ◽

J FOWKE ◽

J RANDALL

Keyword(s):

Kinetics Of ◽

Kinetics Of Inhibition ◽

Neurotoxic Esterase ◽

Brain Acetylcholinesterase

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Inhibition of Hen Brain Acetylcholinesterase and Neurotoxic Esterase by Chlorpyrifos in Vivo and Kinetics of Inhibition by Chlorpyrifos Oxon in Vitro: Application to Assessment of Neuropathic Risk

Toxicological Sciences ◽

10.1093/toxsci/20.3.273 ◽

1993 ◽

Vol 20 (3) ◽

pp. 273-279 ◽

Cited By ~ 1

Author(s):

RUDY J. RICHARDSON ◽

THOMAS B. MOORE ◽

USAMAH S. KAYYALI ◽

JAY H. FOWKE ◽

JOSEPH C. RANDALL

Keyword(s):

Kinetics Of ◽

Kinetics Of Inhibition ◽

Neurotoxic Esterase ◽

Brain Acetylcholinesterase

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The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655562 ◽

1966 ◽

Vol 16 (01/02) ◽

pp. 277-295 ◽

Cited By ~ 1

Author(s):

A Silver ◽

M Murray

Keyword(s):

Amino Acids ◽

Competitive Inhibition ◽

Amorphous Material ◽

Peptide Bond ◽

Initial Reaction ◽

Reaction Products ◽

Coagulation Mechanism ◽

Kinetics Of ◽

Kinetics Of Inhibition ◽

Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

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