Expression and characterization of the @entity3964 haemoglobinase XXXX .

@entity1522 @entity1605 @entity462 @entity368 @entity3354 @entity3964 @entity311
In the @entity311 parasite @entity3964 , erythrocytic trophozoites hydrolyse haemoglobin to provide @entity1522 for parasite protein synthesis. @entity462 protease inhibitors block parasite haemoglobin hydrolysis and development, indicating that @entity462 proteases are required for these processes. Three papain-family @entity462 protease sequences have been identified in the @entity3964 genome, but the specific roles of their gene products and other plasmodial proteases in haemoglobin hydrolysis are uncertain. @entity1605 was recently identified as a principal trophozoite @entity462 protease and potential drug target. The present study characterizes the related @entity3964 @entity462 protease @entity3354 . As is the case with @entity1605 , @entity3354 is expressed by trophozoites and appears to be located within the food vacuole, the site of haemoglobin hydrolysis. Both proteases require a reducing environment and acidic pH for optimal activity, and both prefer peptide substrates with @entity368 at the P(2) position. The proteases differ, however, in that @entity3354 undergoes efficient processing to an active form only at acidic pH, is more active and stable at acidic pH, and has much lower specific activity against typical papain-family peptide substrates, but has greater activity against native haemoglobin. Thus @entity3354 is a second @entity3964 haemoglobinase that is particularly suited for the hydrolysis of native haemoglobin in the acidic food vacuole. The redundancy of @entity462 proteases may offer optimized hydrolysis of both native haemoglobin and globin peptides. Consideration of both proteases will be necessary to evaluate @entity462 protease inhibitors as antimalarial drugs.
