PEGylation effect on StAP3 cytotoxic activity

FERNANDO MUÑOZ; PABLO CARACCIOLO; GUSTAVO DALEO; GUSTAVO ABRAHAM; MARÍA G. GUEVARA.

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2012

PEGylation (i.e. the covalent link of PEG chains) is a technique used to improve pharmaceutical properties of bioactive proteins and peptides, mainly by improving the serum half-life, and reducing the immunogenicity and the enzymatic degradation. We have previously reported the purification and characterization of potato aspartic proteases (StAPs) with antimicrobial/antitumor activity. Selective cytotoxic activity of StAPs suggests that, these proteins could be used to develop alternative drugs to contribute to resolve the increasing resistance of pathogenic bacteria to conventional antibiotics. In this work, the ability of PEGylation to improve StAPs antimicrobial activity is analyzed. PEGylation of StAP3 was performed at pH 6 and 8, obtaining higher performance at pH 8. The results show that PEG-conjugated StAP3 exerts cytotoxic activity towards Fusarium solani. The estimated values of IC50 obtained for PEG-conjugated StAP3 and free StAP3 were 9 μg/ml and 28 μg/ml, respectively. Like free StAP3, PEG-conjugated StAP3 is able to interact and to permeabilize spores and hyphae plasma cell membranes in a dose-dependent manner. The results obtained here indicate that PEGylation increases the cytotoxic activity of StAP3.