Purification and characterization of a small cationic protein from the tobacco hornworm Manduca sexta.

ABSTRACT: The prophenoloxidase (proPO) activation system is an important defense mechanism in arthropods, and activation of proPO to active phenoloxidase (PO) involves a serine proteinase cascade. Here, we report the purification and characterization of a small cationic protein CP8 from the tobacco hornworm, Manduca sexta, which can stimulate proPO activation. BLAST search showed that Manduca CP8 is similar to a fungal proteinase inhibitor-1 (AmFPI-1), an inducible serine proteinase inhibitor-1 (ISPI-1), and other small cationic proteins with unknown functions. However, we showed that Manduca CP8 did not inhibit proteinase activity, but stimulated proPO activation in plasma. When small amount (0.1 microg) of purified native CP8 or BSA was added to cell-free plasma samples and incubated for 20 min, l

SUBMITTER: Ling E 

PROVIDER: S-EPMC2659724 | biostudies-literature | 2009 Apr

REPOSITORIES: biostudies-literature