Mass spectrometry in snake venom research

Abstract

Mass spectrometry allows rapid and reliable identification and characterisation of proteins and peptides in snake venoms. With the increasing availability of transcriptomic and genomic data, there is a growing database of protein sequences that is essential for protein identification. Snake venoms are analysed using a multi-dimensional proteomic approach known as ‚venomics‘. Proteins are first separated by one- or two-dimensional gel electrophoresis or reversed-phase liquid chromatography. The individual protein spots or fractions are digested enzymatically and the resulting peptides are analysed by mass spectrometry. The proteins are identified by comparing the mass spectra of the peptides with those in the database. High-performance mass spectrometers allow the analysis of venoms even without prior separation of the protein mixture. We have analysed the protein composition (proteome) of two European snake venoms of greatest medical interest, the nose-horned viper (Vipera a. ammodytes) and the common adder (Vipera b. berus). The nose-horned viper is the most venomous European snake. Although its bite is rarely fatal, a human wictim often needs to be observed in hospital and treated with an antivenom. The adder is the most widespread European venomous snake and its bite causes milder symptoms than the bite of the nose-horned viper in most cases. To explain the observed differences in the effects of the two venoms at the molecular level, a proteomic study was performed. We also analysed the proteome of the venom of the meadow viper (Vipera ursinii), the most threatened snake species in Europe. It does not pose a threat to humans. In the wild, it feeds mainly on insects, while in captivity it is fed on mice. A comparison of the proteome of the venom of snakes in the wild and snakes in captivity showed clear differences. Thus, the composition of snake venom is diet-dependent. Mass spectrometry is also a very useful tool in the characterisation of antivenoms (antivenomics) to determine their specificity and neutralising power.