Proteases play an active role in all living organisms. In plants, they exhibit
essential roles in various biological processes throughout the life cycle by proteolysis,
like cell growth and development, differentiation, seed germination, reproduction,
senescence, development of stomata, chloroplast biogenesis, apoptosis, plant
resistance, etc. Nowadays, it is a well-known group of enzymes for its industrial and
therapeutic values. Plant proteases viz. papain (papaya), bromelain (pineapple), ficin
(fig tree), and cucumisin (melon) are well-characterized proteases that have medicinal
values for the treatment of upset stomach, diabetic thrombosis, wounds, tumor, asthma,
angina, rheumatoid arthritis, bronchitis, sinusitis, etc. In addition, some common Indian
spices are found to be good sources of natural proteases, such as Withania coagulans
(vegetable rennet), Carum copticum (Ajwain), Syzygium aromaticum (Clove), Cuminum
cyminum (Cumin), Nigella sativa (black cumin), Cinnamomum verum (Cinnamon),
Foeniculum vulgare (common fennel), Zingiber officinale (ginger), Cinnamomum
tamala (Indian Cassia), Curcuma longa (turmeric), etc. which have traditional usage as
healing agents in multiple disorders. This chapter highlights the pharmaceutical,
industrial and biotechnological aspects of various plant proteases as well as the
structure, properties and catalytic mechanisms.