Chromatographic behavior of Bothrops erythromelas phospholipase and other venom constituents on Superdex 75

In a chromatographic method modification intended to preserve protease activity in Bothrops erythromelas venom, 2 mM CaCl2 was added to the gel filtration buffer [50mM Tris/HCl/150mM NaCl (pH 8.0)], in lieu of an equimolar portion of NaCl. This minor compositional change induced significant differences in the venom elution profile on Superdex 200. For this reason, the influence of buffer composition on chromatographic behavior was investigated using an analytical Superdex 75 HR 10/30 column. Phospholipase (PLA) was used as a marker because Naja atra PLA had previously been observed to interact hydrophobically with this resin. PLA elution volumes generally increased as buffer pH decreased. Addition of 20% acetonitrile to the Tris buffer with CaCl2, reduced hydrophobic interaction of the PLA so significantly that its elution was non-overlapping in the two buffers. Other venom constituents, including bradykinin-potentiating peptides and probable hemorrhagic metalloproteases, were similarly affected. Buffer calcium, bound by vicinal dextran hydroxyl groups, appears to retard elution of this acidic PLA.