What is the Difference Between Metalloenzymes and Metal Activated Enzymes?

🆚 Go to Comparative Table 🆚

The main difference between metalloenzymes and metal-activated enzymes lies in the binding of metal ions and their specificity for certain metal ions:

  • Metalloenzymes generally contain a specific metal ion and require a precise metal ion for their activity. These enzymes tend to be rather specific for a particular metal ion due to tight binding, which is usually the result of specific metal-ligand interactions. Some examples of metalloenzymes include zinc-containing carbonic anhydrase and iron-sulfur enzymes.
  • Metal-activated enzymes can use any of several metal ions of similar size and charge, and their activity increases due to the presence of these metal ions. These enzymes do not have a firmly bound metal ion as a cofactor, and they require a high concentration of metal ions around them for activity. The binding of metal ions to metal-activated enzymes is largely electrostatic in nature, allowing several different metal ions with similar charges and sizes to be used to give an active enzyme.

In summary, while both types of enzymes require metal ions for their catalytic activity, metalloenzymes are more specific in their metal ion requirement due to tight binding, whereas metal-activated enzymes are less specific and can use multiple metal ions with similar charges and sizes for activity.

Comparative Table: Metalloenzymes vs Metal Activated Enzymes

The main difference between metalloenzymes and metal-activated enzymes lies in the way the enzyme binds to the metal ions. Here is a comparison table highlighting the differences between the two:

Feature Metalloenzymes Metal-Activated Enzymes
Definition Enzymes that contain a tightly bound metal ion as a cofactor, which forms coordinate covalent bonds with the amino acids of the enzyme or a further coordination sphere ligand. Enzymes that have an increased activity due to the presence of a metal ion but do not have a firmly bound metal ion as a cofactor.
Metal Ion Binding The metal ion is firmly bound to the enzyme and forms coordinate covalent bonds with the amino acids of the enzyme or a further coordination sphere ligand. The binding of the metal ion to the enzyme is largely electrostatic in nature, and several different metal ions with similar charges and sizes can often be used to give an active enzyme.
Specificity Metalloenzymes are more specific in their ability to catalyze certain types of reactions because they generally contain a specific metal ion. Metal-activated enzymes have less specific active sites and can catalyze a wider range of reactions.
Stability Metalloenzymes are more stable and require less metal activator to function. Metal-activated enzymes are less stable and require a smaller amount of metal activator to function.