Open Access1,4–Diamino‐2‐butyne as the mechanism‐based pea diamine oxidase inhibitor
Author(s) -
PEČ Pavel,
FRÉSORT Ivo
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb17333.x
Subject(s) - diamine oxidase , chemistry , substrate (aquarium) , reagent , enzyme kinetics , pyrrole , enzyme , diamine , active site , covalent bond , non competitive inhibition , nucleophile , stereochemistry , kinetics , medicinal chemistry , reaction mechanism , catalysis , organic chemistry , biology , physics , quantum mechanics , ecology
1,4‐Diamino‐2‐butyne is a mechanism‐based inhibitor of diamine oxidase (EC 1.4.3.6) from pea cotyledons. It shows saturation kinetics K m = 1 mM like a substrate, but its interaction leads to time‐dependent loss of enzyme activity which is not restored by gel filtration. The substrate 1,4‐diaminobutane and the competitive inhibitor 1,4‐diamino‐2‐butanone protect the enzyme against inactivation. Changes in the enzyme electronic spectra with 1,4‐diamino‐2‐butyne were found. The mechanism of the interaction involves an intermediate aminoallenic compound, which is formed with covalent bound pyrrole in the reaction of the nucleophile with the enzyme. The presence of a pyrrole in the inactivated enzyme was confirmed by reaction with Ehrlich's reagent. The kinetic data obtained in this study indicate that 1,4‐diamino‐2‐butyne is a mechanism‐based inactivator with number of turnovers, r = 17 and characteristic constants K′ = 0.32 mM and k m = 4.89 min −1 .