Pharma Sci -Trypsin: A Novel Scavenger of Superoxide Anion - Xin Li- Henan University of Science and Technology


Reactive oxygen species (ROS) is a class of ubiquitous molecules including superoxide anion (O2 -.), hydrogen peroxide (H2O2), and hydroxyl radicals. ROS regulates critical steps in the signal transduction cascades and many important cellular events, such as protein phosphorylation, gene expression, transcription factor activation, DNA synthesis, and cell proliferation. On the other hand, ROS are toxic to cells, due to their damage on cellular components. It was hypothesized that O2 -. produced by bacterial mammalian pathogens such as E. faecalis might play as a virulence factor. As a result, intracellular defenses against superoxide-mediated damage are robust.

Protection from ROS may include the production of endogenous enzymes such as catalase, which degrades H2O2 and superoxide dismutase (SOD), which dismutase O2.

Trypsin is a serine protease found in the digestive system of many vertebrates, where it hydrolyses proteins. In our pervious works, trypsin was found to be able to scavenge O2 -. with the concurrent production of H2O2 in the culture of bacteria. The objective of this paper is to characterize this O2 -. scavenging activities of trypsin, both in vivo and in vitro. Results showed that the activities of trypsin are independent O2 -. scavenging enzyme in organisms.



The Escherichia coli wild type strain (MG1655) used in our works was kindly supplied by Prof. James A. Imlay at Department of Microbiology, University of Illinois, and Urbana. Strain MG1655 was maintained on LB medium and cultured at 37°C for 48 h. A single colony was cultured in LB liquid medium for an additional 24 h to obtain a suspension of approximately 109 cells per ml. The strain was conserved in glycerol and stored at -20°C until use.

Author(s): Xin Li

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