Phospholipase A2-interacting weak neurotoxins from venom of monocled cobra Naja kaouthia display cell-specific cytotoxicity

The molecular weights of two phospholipase A2 (PLA2)-interacting polypeptides (kaouthiotoxins (KTXs)—KTX-A and KTX-B) purified from the venom of monocled cobra Naja kaouthia, were estimated by mass spectrometry as 7722 and 7627 Da, respectively. Binary sequence alignment showed that both KTXs share substantial sequence homology with weak neurotoxins from cobra venom and they were devoid of any enzymatic activity. Their pI was determined at pH 8.1 showing basic nature of these proteins. KTXs displayed cell-specific cytotoxicity on mammalian and insect cells.