Characterization of Libyan Cobra (Naja haje) Venom using Fluorescence and UV-Visible Spectroscopy

Abstract

Snake venoms act as a preparative to defend animals against predators and helps in immobilizing and digestion of prey. Venoms consist of a combination of enzymes and toxins, such as metalloproteases, phospholipase A2, L-amino acid oxidase and toxins, including cytotoxins and neurotoxins. In addition to their toxicity, venom components exhibit several pharmacological activities and can be used as templates for drug design. The Libyan cobra venom was studied using UV-visible and fluorescence spectroscopic techniques. The cobra protein main chain absorbs light in the region of 240-340nm. The aromatic side-chains of cobra venom contain tyrosine, tryptophan and phenylalanine which are responsible for the absorbance in this region. Cobra venom provides intrinsic fluorescence emissions due to excitation of tryptophan residues, with some contribution from phenylalanine and tyrosine emissions. In addition, disulphide bridges contribute considerable absorption in this wavelength range. The main fluorescence obtained is due to tryptophan which has a wavelength of maximum absorption at 280 nm and an emission peak ranging from 310 to 350 nm. UV-visible absorption and fluorescence spectroscopic techniques are sensitive and rapid to study cobra venom in order to better comprehend the performance of this venom.