A 3D render of an enzyme
Enzymes that catalyze the most important biological reactions generally have only one function. Other enzymes can carry out multiple less important reactions. From Science News:
Of the 1,081 enzymes studied, 404 were generalists that carried out multiple chemical reactions. The 677 specialist enzymes, it turned out, were essential for the bacterium’s survival, for example tasked with turning genetic instructions into proteins.
Revealing where the generalists and specialists do their stuff in a metabolic network could help scientists identify starter enzymes for designing new drugs, fuels and other chemical products. It also may help biologists create organisms from scratch, says Pablo Carbonell, a synthetic biologist at the University of Évry-Val-d’Essonne in France.
The work clears up a long-standing question about promiscuity and monogamy among enzymes. Enzymes act on what scientists call substrates; for example amylase, an enzyme in saliva, breaks down the substrate starch. For more than 100 years enzymes have been presented as exceedingly loyal to their substrates. But the growing number of promiscuous enzymes that interact with multiple substrates and carry out multiple reactions have forced scientists to face the fact that all enzymes aren’t the dedicated, loyal players they’ve been made out to be.