Binding Analysis of a Novel Peptide to Plasmodium falciparum Knob-Associated Histidine Rich Protein (KAHRP)

Abstract

Knob-associated histidine rich protein (KAHRP) is secreted by  Plasmodium falciparum  in infected red blood cells. This protein is required for the production of surface protrusions called knobs, which have been shown to be crucial for the adherence of  P. falciparum -infected erythrocytes ( Pf -IRBC) to the endothelia of small blood vessels. KP-AP, a 10-amino acid (AA) peptide (FITRANDTSK), binds specifically with KAHRP in preliminary studies. KP-AP is expected to disrupt knob formation and prohibit adherence of  Pf -IRBC to blood vessels and greatly reduce the pathogenicity of the parasite. This paper describes an investigation into the binding interaction between biotinylated KP-AP (Biotin-AP) and a segment of KAHRP. ELISA and the real-time bio-interaction optical sensor, BIAcore are the methods of detection. The specific binding was confirmed with ELISA and the KD value was estimated to be 1.2 μM. Binding was not detected with BIAcore, most likely due to the reduced flexibility of Biotin-AP while immobilized on the sensor chip.