Proteolytic Activation of Prophenoloxidase in an Insect Manduca Sexta

  • Haobo Jiang
  • Yang Wang
  • Michael R. Kanost
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 484)


Phenol oxidase (PO) (EC1.14.18.1) is important in cuticular sclerotization and in defense against pathogens and parasites (Söderhäll et al., 1996; Sugumaran, 1996; Ashida and Brey, 1998). PO catalyzes hydroxylation of monophenols to o-diphenols and oxidation of o-diphenols to quinones. The quinones take part in sclerotization of cuticle and serve as precursors for synthesis of melanin. PO is synthesized in arthropods as an inactive zymogen, prophenoloxidase (proPO), which can be activated by proteolytic cleavage at a specific site in the protein. Wounding of an insect or exposure to certain microbial polysaccharides leads to the activation of a proteinase that specifically activates proPO, perhaps at the last step of a proteinase cascade (Ashida and Brey, 1998). The reactions catalyzed by PO then can result in melanization of foreign organisms trapped in capsules or hemocyte nodules (Gillespie et al., 1997).


Horseshoe Crab Phenol Oxidase Amidase Activity Phenol Oxidase Activity Microbial Polysaccharide 
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Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • Haobo Jiang
    • 1
  • Yang Wang
    • 1
  • Michael R. Kanost
    • 1
  1. 1.Department of BiochemistryKansas State UniversityManhattan

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