Introduction to the thematic minireview series on enzyme evolution

Enzyme promiscuity in earthworm serine protease: substrate versatility and therapeutic potential

Enzymes are the most versatile molecules in the biological world. These amazing molecules play an integral role in the regulation of various metabolic pathways and physiology subsequently. Promiscuity of an enzyme is the capacity to catalyze additional biochemical reactions besides their native one. Catalytic promiscuity has shown great impact in enzyme engineering for commercial enzyme and therapeutics with natural or engineered catalytic promiscuity. The earthworm serine protease (ESP) is a classic example of enzyme promiscuity and studied for its therapeutic potential over the last few decades. The ESP was reported for several therapeutic properties and fibrinolytic activity has been much explored. ESP, a complex enzyme exists as several isoforms of molecular weight ranging from 14 to 33 kDa. The fibrinolytic capacity of the enzyme has been studied in different species of earthworm and molecular mechanism is quite different from conventional thrombolytics. Cytotoxic and anti-tumor activities of ESP were evaluated using several cancer cell lines. Enzyme had shown tremendous scope in fighting against plant viruses and microbes. ESP is also reported for anti-inflammatory activity and anti-oxidant property. Apart from these, recently, ESP is reported for DNase activity. The daunting challenge for researchers is to understand the molecular mechanism for such diverse properties and possibility of enzyme promiscuity. This review emphasizes molecular mechanism of ESP governing various biochemical reactions. Further, the concept of enzyme promiscuity in ESP towards development of novel enzyme based drugs has been reviewed in this study.