Identification of a peptide derived from a Bothrops moojeni metalloprotease with in vitro inhibitory action on the Plasmodium falciparum purine nucleoside phosphorylase enzyme (PfPNP)

Abstract There is a growing need for research on new antimalarial agents against Plasmodium falciparum infection, especially in regards to planning molecular architecture for specific molecular targets of the parasite. Thus, a metalloprotease from Bothrops moojeni , known as BmooMPα-I, was explored in this study, through in silico assays, aiming at the development of a peptide generated from this molecule with potential inhibitory action on P f PNP, an enzyme necessary for the survival of the parasite. In order to isolate BmooMPα-I, cation exchange and reverse phase chromatographies were performed, followed by in vitro assays of antiparasitic activity against the W2 strain of P. falciparum . The interactions between BmooMPα-I and P f PNP were evaluated via docking, and the resulting peptide, described as Pep1 BM, was selected according to the BmooMPα-I region demonstrating the best interaction score with the target of interest. The values for the specific activities of the P f PNP reaction were measured using the inorganic phosphate substrate and MESG. The fraction corresponding to BmooMPα-I was identified as fraction 4 in the cation exchange chromatography step, due to proteolytic activity on casein and the presence of a major band at ≅ 23 kDa. BmooMPα-I was able to inhibit in vitro growth of W2 P. falciparum , with an IC 50 value of 16.14 μg/mL. Virtual screening with Pep1 BM demonstrated two P f PNP target binding regions, with ΔG values at the interaction interface of −10.75 kcal/mol and −11.74 kcal/mol. A significant reduction in the enzymatic activity of P f PNP was observed in the presence of Pep 1 BM when compared to the assay in the absence of this possible inhibitor. BmooMPα-I showed activity in vitro against W2 P. falciparum . By means of in silico techniques, the Pep 1 BM was identified as having potential binding affinity to the catalytic site of P f PNP and of inhibiting its catalytic activity in vitro .