That is, what it participates in is breaking different types of peptide bonds breaking different types of proteins that we ingest into our body. And finally, the final mechanism by which our enzymes can decrease the activation energy and therefore increase the rates of reactions is called metal ion catalysis. So, what's so special about metal ions or metal atoms? Well, many enzymes and many proteins inside our body. For example, when we spoke about myoglobin and hemoglobin we saw that these proteins use metal atoms and in fact, enzymes utilize metal atoms as cofactors. Now, what's so special about these metal atoms?