Comparative analysis of the high molecular mass subproteomes of eight Bothrops snake venoms

Snake venoms are extremely active biological secretions composed primarily of various classes of enzymes. The genus Bothrops comprises various pit viper species that represent the most medically significant taxa in Central and South America, accounting for more human envenomations and fatalities than any other snakes in the region. Venom proteomes of many Bothrops species have been well-characterized but investigations have focused almost exclusively on proteins smaller than 100 kDa despite expression of larger components being documented in several Bothrops venoms. This study sought to achieve detailed identification of major components in the high molecular mass subproteome of venoms from eight Bothrops species (B. brazili, B. cotiara, B. insularis, B. jararaca, B. jararacussu, B. leucurus, B. moojeni and B. neuwiedi). Enzymes such as metalloproteinases and L-amino acid oxidases were the most prominent components identified in the first size-exclusion chromatography fractions of these venoms. Minor components also identified in the first peaks included 5'-nucleotidase, aminopeptidase, phosphodiesterase, and phospholipases A₂ and B. Most of these components disappeared in electrophoretic profiles under reducing conditions, suggesting that they may be composed of more than one polypeptide chain. A significant shift in the molecular masses of these protein bands was observed following enzymatic N-deglycosylation, indicating that they may contain N-glycans. Furthermore, none of the identified high molecular mass proteins were shared by all eight species, revealing a high level of interspecific variability among these venom components.