Analysis of the kinetics of reversible enzyme inhibition by a general algebraic method. Application to multisite inhibition of the phosphoglycerate kinase from Trypanosoma brucei.
The action of an inhibitor on a stationary enzyme reaction is described by a simple equation, which reflects how the progressive binding of inhibitor molecules influences the existence and the productivity of the enzyme forms. This allows deduction of the structure of the enzyme system from the experimental results, using new type of plots (1/[I], 1/[I](a)v) where a = 0,1,2,... in complement to the usual graphs. A reaction scheme is thereby logically built. This method may be used without any theoretical calculation. It is valid whatever the inhibitor, when the association reactions of the substrates and the inhibitor to the enzyme are in rapid equilibrium, and with dead end inhibitors, more generally for steady state enzyme reactions. This method may be adapted to enzyme activation. An original inhibition mode is described with particular bifunctional molecules: cooperative binding of the inhibitor to the enzyme, outside the active site, by direct mutual interaction of two inhibitor molecules, and locking of the conformational changes that normally precede the release of the products.
Puech
J
J
Laboratoire de Microscopie et Structure des Matériaux, Université Paul Sabatier, Toulouse, France.
Callens
M
M
Willson
M
M
D000818:Animals; D001665:Binding Sites; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D008433:Mathematics; D015394:Molecular Structure; D010735:Phosphoglycerate Kinase / Q000037:antagonists & inhibitors*; D010795:Phthalic Acids / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D013498:Suramin / Q000494:pharmacology; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
D004791:Enzyme Inhibitors; D010795:Phthalic Acids; D013498:Suramin; D010735:Phosphoglycerate Kinase