Ribonucleasa A, 1 g

Enzyme: a neoclassical, Greek artificial word ενζυμου, énzymon, derived from εν-, en- (in-) and ζυμη, zýmé (yeast, sourdough, archaic)
Ferments: comes from the Latin fermentum (ferments, sourdough)

There are six classes in which all enzymes are classified according to the particular reaction they catalyse:

• Oxidoreductases (catalyse redox reactions)

• Transferases (transfer functional groups among substrates)

• Hydrolases (cleave bonds via addition of water)

• Lyases/Synthases (cleave or synthesise complex products out of basic substrates without cleavage of ATP)

• Isomerases (transform chemical isomers)

• Ligases/Synthetases (cleave or synthesise complex products out of basic substrates via cleavage of ATP)