Compilation of enzyme-modifier mechanisms
Although all 17 basic kinetic mechanisms by which enzymes interact with their modifiers have been amply documented in the literature, recognizing their identity is not always straightforward. The reasons span between inconsistent nomenclature, dissimilar mechanisms pooled under the same name (with noncompetitive inhibition leading the inventory), to missing documentation.
The 17 + 1 pages of this section present, in tabular form and random order, a compilation of published results of enzyme inhibition and activation. This compilation is neither a database, nor the lists are intended to cover all published results, an unmanageable task. Updates may follow by appending new, representative examples to those already existing. Following the presentation of examples of the 17 basic modifier mechanisms, a handy, searchable table (LIST OF ALL EXAMPLES) will summarize all items.
Independently of nomenclature, all papers featured in this section provided sufficient documentation and sound experimental evidence for assigning kinetic mechanisms without ambiguity. When their identity could not be understood at a glance, data presented in graphical or tabular form were elaborated with the methods described in the section Data analysis of this website to reveal the nature of the underlying interactions between enzymes and their modifiers.
Each example, in one row, shows the following information in seven columns:
- Progressive number of the entries for internal cross reference
- Enzyme names as recommended by the International Union of Biochemistry and Molecular Biology (IUBMB) and BRENDA, followed by the name of the organism as Genus species
- Name of the modifier
- Name of the substrate, always the varied substrate to which inhibition or activation refers
- Name of the mechanism as specified in the original reference
- Reference as first author and publication year
Comments are shown below the tables, followed by the references in alphabetical order and numbered for practical reasons. All references are linked to PubMed, where in many cases full text links (often free) are provided. The structural formulas of some modifiers and substrates are provided.
Access the examples either from the menu bar or by clicking the acronyms in the following table
|1||LSpI||Linear specific inhibition|
|2||LCaI||Linear catalytic inhibition|
|3||LMx(Sp>Ca)I||Linear mixed, predominantly specific inhibition|
|4||LMx(Sp<Ca)I||Linear mixed, predominantly catalytic inhibition|
|5||LMx(Sp=Ca)I||Linear mixed, balanced inhibition|
|6||HSpI||Hyperbolic specific inhibition|
|7||HCaI||Hyperbolic catalytic inhibition|
|8||HMx(Sp>Ca)I||Hyperbolic mixed, predominantly specific inhibition|
|9||HMx(Sp<Ca)I||Hyperbolic mixed, predominantly catalyic inhibition|
|10||HMx(Sp=Ca)I||Hyperbolic mixed, balanced inhibition|
|11||HMxD(I/A)||Hyperbolic mixed, dual modification (inhibition→activation)|
|12||HCaA||Hyperbolic catalytic activation|
|13||HMx(Sp>Ca)A||Hyperbolic mixed, predominantly specific activation|
|14||HMxD(A/I)||Hyperbolic mixed, dual modification (activation→inhibition)|
|15||HSpA||Hyperbolic specific activation|
|16||HMx(Sp<Ca)A||Hyperbolic mixed, predominantly catalytic activation|
|17||HMx(Sp=Ca)A||Hyperbolic mixed, balanced activation|