Endopeptidase or endoproteinase are proteolytic peptidases that break peptide bonds of nonterminal amino acids (i.e. within the molecule), in contrast to exopeptidases, which break peptide bonds from end-pieces of terminal amino acids.
[1] For this reason, endopeptidases cannot break down peptides into monomers, while exopeptidases can break down proteins into monomers.
A particular case of endopeptidase is the oligopeptidase, whose substrates are oligopeptides instead of proteins.
They are usually very specific for certain amino acids.
Examples of endopeptidases include: