ABSTRACT
This chapter examines degradative enzymes as classes, specifically proteases, glycosidases and phospholipases. It focuses on pathogen proteases that degrade host proteins, proteases produced by pathogens are involved in degrading pathogen surface proteins once they have performed their function(s). Many extracellular proteases are secreted in an inactive form termed a zymogen. Proteases may have a narrow or broad range of specificity. Microbial proteases inactivate plasma serine protease inhibitors. Two saprophytic bacteria, Clostridium perfringens and Pseudomonas aeruginosa, whose natural habitat is soil and water but are also opportunistic bacterial human pathogens, produce a plethora of degradative enzymes. In addition to secreted degradative enzymes that degrade host molecules, both pathogenic prokaryotes and eukaryotes possess cytoplasmic and membrane proteases that play important roles in controlling expression and solubility of determinants of pathogenesis. The role(s) of degradative enzymes in pathogenesis depend on the environments in which the bacteria that produce them operate.
