Abstract
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.
MeSH terms
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Animals
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Binding Sites
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Binding, Competitive
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Cattle
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Chymotrypsin / metabolism
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Cysteine Endopeptidases / isolation & purification
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Cysteine Endopeptidases / metabolism*
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Kinetics
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Lung / enzymology*
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Multienzyme Complexes / antagonists & inhibitors
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Multienzyme Complexes / isolation & purification
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Multienzyme Complexes / metabolism*
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Protease Inhibitors / metabolism*
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Protease Inhibitors / pharmacology
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Proteasome Endopeptidase Complex
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Protein Binding
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Sodium / pharmacology*
Substances
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Multienzyme Complexes
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Protease Inhibitors
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Sodium
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Chymotrypsin
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Cysteine Endopeptidases
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Proteasome Endopeptidase Complex