Multiple binding of thallium and rubidium to potassium-activated yeast aldehyde dehydrogenase. Influences on tertiary structure, stability and catalytic activity.
Univalent cation activators of aldehyde dehydrogenase have dual effects, both interpreted as cation-induced or -stabilized conformation changes. These two processes are differentiated by the time scales of their associated changes in activity. Using Tl+ as an activator, under certain conditions, the slower change in activity saturates at a Tl+ concentration which is only 0.1 Ks for the faster change. This, together with evidence for cation-induced rather than cation-stabilized conformation changes, is used to propose separate binding sites for cations responsible for the two activation processes. Equilibrium dialysis indicates 4 binding sites per active site for Rb+ or 6 sites for Tl+. At least one of the additional sites for Tl+ is an inhibitory site which has been differentiated from the activator sites on the basis of steady-state and pre-steady-state kinetic data.
D000444:Aldehyde Dehydrogenase; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D001665:Binding Sites; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008956:Models, Chemical; D011188:Potassium / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D012413:Rubidium / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013793:Thallium / Q000378:metabolism* / Q000494:pharmacology
D013793:Thallium; D000445:Aldehyde Oxidoreductases; D000444:Aldehyde Dehydrogenase; D012413:Rubidium; D011188:Potassium