Proteases: Our Friends or Foes

In the human body there are at least 500-600 different proteases, the enzymes capable to catalyze hydrolysis of peptide bond in the proteins. The process of proteolysis is responsible for many physiological processes such as amino acid recycling, removing of aged, misfolded or damaged proteins, development and differentiation, antigen presentation, apoptosis, necrosis, inflammation, cell signaling, survival, and proliferation, wound healing, and immunity. This chapter will provide an overview of the main classes of proteases and the common criteria used for their classification (type of reaction catalyzed, chemical nature of the catalytic site (metalloproteases, aspartic, glutamic, threonine, serine, and cysteine proteases)). In addition to that, evolutionary relationship with reference to diversity of protease structures (MEROPS and Degradome databases), as well as mechanisms of proteolysis reaction, and of regulation of proteases activity, including their substrates and inhibitors, will be enclosed. Further, chapter progresses into proteases distribution pattern within the human’s tissues in healthy condition. The special attention will be dedicate to cathepsins, caspases, calpains and matrix metalloproteases, the most studied four classes of proteases in different physiological and pathological conditions. Their classification, localization in cell, expression pattern, substrates and mechanisms of regulation of activity will be given in respect to obesity, diabetes, insulin resistance, and the most common four types of cancer (gastric, ovarian, breast, and lung). Also, the brief overview of proteases, proposed as the potential diagnostic, prognostic markers and therapeutic targets, will be elaborated. The chapter encompasses with advantages and disadvantages of endogenous and exogenous protease inhibitors application in the potential treatment of like cardiovascular, neurodegenerative, cancer diseases