Related Experiment Video
Updated: Aug 13, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Kinetic analysis of ligand-induced autocatalytic reactions
1National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Academia Sinica, Beijing 100101, People's Republic of China.
Abstract:
Protein phosphorylation and limited proteolysis are two most common regulatory mechanisms involving the energy-dependent covalent modification of regulatory enzymes. In addition to modifying other proteins, many protein kinases and proteases catalyse automodification reactions (i.e. reactions in which the kinase or zymogen serves as its own substrate), and their activities are frequently regulated by other regulatory ligands. In the present study, a kinetic analysis of autocatalytic reaction modulated by regulatory ligands is presented. On the basis of the kinetic equation, a novel procedure is developed to evaluate the kinetic parameters of the reaction. As an example of an application of this method, the effects of calcium ions on the autoacatalytic activation of trypsinogen by trypsin is re-examined. The results indicate that the binding affinity for Ca2+-bound trypsinogen to trypsin is at least two orders of magnitude higher than that for Ca2+-free trypsinogen, and therefore that the effect of Ca2+ ions on K(m*) values for trypsinogen is very much greater than that for the model peptides. Based on the experimental results, one possible molecular mechanism has been proposed.
Related Concept Videos
Catalysis
Introduction to Mechanisms of Enzyme Catalysis
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Introduction to Mechanisms of Enzyme Catalysis
Catalysis
Heterogeneous Catalysis

