The bovine lung 20S proteasome binding to reversible inhibitors: modulation by sodium ion.
The effect of sodium ion on the inhibition exerted by Cbz-Leu-Leu-Leu-CHO on the chymotrypsin-like activity of the 20S proteasome isolated from bovine lung was investigated. The experimental data were analyzed using a standard linkage formalism. The calculated equilibrium affinity constants for the sodium ion binding to the free-enzyme and the inhibitor-bound enzyme are compatible to other well-characterized ion-involving heterotropic systems. The functional interdependence between the binding events played by the inhibitor and the sodium ion conforms to a heterotropic modulatory mechanism.
Eleuteri
Anna Maria
AM
Post-Graduate School in Clinical Biochemistry, Department of Molecular, Cellular and Animal Biology, University of Camerino, 62032 (MC), Camerino, Italy. annamaria.eleuteri@unicam.it <annamaria.eleuteri@unicam.it>
Angeletti
Mauro
M
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002417:Cattle; D002918:Chymotrypsin / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008168:Lung / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D011480:Protease Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D012964:Sodium / Q000494:pharmacology*
D009097:Multienzyme Complexes; D011480:Protease Inhibitors; D012964:Sodium; D002918:Chymotrypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex