title: Cholinesterase: substrate inhibition and substrate activation.
abstract: The relationship between activities and substrate concentrations (pS-curves) was analysed for reactions of acetylcholinesterase (EC 3.1.1.7) and butyrylcholinesterase (EC 3.1.1.8). Catalytic constants Km, Kss, Vm, n and b were calculated from the Michaelis, Haldane, Hill and Webb equations in order to assess whether a given substrate also acts as an inhibitor or activator. It is suggested that the term substrate inhibition should only be attributed to substrates revealing bell-shaped pS-curves, while the terms apparent substrate inhibition or apparent substrate activation should relate to calculated values of the catalytic constants.
authors.affiliation: Institute for Medical Research and Occupational Health, Ksaverska cesta 2, POBox 291, HR-10001, Zagreb, Croatia, Croatia.
authors.forename: Elsa
authors.initials: E
authors.lastname: Reiner
authors.affiliation: Institute for Medical Research and Occupational Health, Ksaverska cesta 2, POBox 291, HR-10001, Zagreb, Croatia, Croatia.
authors.forename: Vera
authors.initials: V
authors.lastname: Simeon-Rudolf
keywords: Key words acetylcholinesterase; apparent substrate inhibition and activation.; butyrylcholinesterase; catalytic constants; substrate inhibition and activation