Host defence peptides (HDPs) are powerful modulators of cellular responses to various types
of insults caused by pathogen agents. To date, a wide range of HDPs, from species of different kingdoms
including bacteria, plant and animal with extreme diversity in structure and biological activity,
have been described. Apart from a limited number of peptides ribosomally synthesized, a large number
of promising and multifunctional HDPs have been identified within protein precursors, with properties
not necessarily related to innate immunity, consolidating the fascinating hypothesis that proteins have a
second or even multiple biological mission in the form of one or more bio-active peptides. Among
these precursors, enzymes constitute certainly an interesting group, because most of them are mainly
globular and characterized by a fine specific internal structure closely related to their catalytic properties
and also because they are yet little considered as potential HDP releasing proteins. In this regard,
the main aim of the present review is to describe a panel of HDPs, identified in all canonical classes of
enzymes, and to provide a detailed description on hydrolases and their corresponding HDPs, as there
seems to exist a striking link between these structurally sophisticated catalysts and their high content in
cationic and amphipathic cryptic peptides.
