Proteases

Part of speech: noun

Definitions

1. Enzymes that catalyze the breakdown of proteins into smaller peptides or amino acids by hydrolyzing peptide bonds in proteins
2. Biological catalysts that facilitate the degradation of proteins into simpler forms, such as peptides and amino acids, by cleaving peptide bonds
3. Molecules that act as enzymes to hydrolyze protein structures into smaller units, including peptides and free amino acids, by breaking peptide linkages

Etymology: "Proteases" is simply the plural of "protease", a compound built from "prote(in)" and the suffix "-ase". The "-ase" ending is the one that marks an enzyme, and it came into use through a particular chain of coinages. It was modelled on "diastase", the name given to the first enzyme ever isolated, a starch-digesting substance. The "dia-" part of that name traces back to the Greek "diastasis", meaning a separation or standing apart, so "diastase" was a word built on a notion of splitting things up, and the "-ase" ending was lifted from it. The first half of the word, "prote(in)", comes from the Greek "prōteios", meaning primary or of first importance. Chemists picked that name for the substance in 1838, when the Dutch chemist Gerardus Johannes Mulder proposed "protein" for the class of nitrogen-rich compounds found in living tissue. Joining it to "-ase" gave a name for any enzyme that breaks proteins apart, which is why the word reads as a plain description of what the substance does.