Ribonuclease from cobra snake venom: purification by affinity chromatography and further characterization

A ribonuclease from cobra snake venom was isolated and purified to homogeneity using antibody-affinity chromatography, increasing the yield fourfold. The purified enzyme showed cytidylic acid specificity, as reported earlier. Further, the effects of temperature, pH, metal ions, inhibitors, and urea on the enzyme activity were studied. Snake venom RNase exhibited salt-dependent reversible association-dissociation behaviour. Immunological studies indicate that this enzyme shares one of the antigenic sites of RNase A. The partial N-terminal sequence of the enzyme showed considerable homology with phospholipases from snake venom; however, the enzyme itself did not show any phospholipase activity.

Antigenic sites on ribonuclease A. Synthetic peptides corresponding to the sites 37-42 and 83-88 on ribonuclease A show immunogenicity

Two hexapeptides NH2-Lys-Asp-Arg-Cys-Lys-Pro-COOH and NH2-Asp-Cys-Arg-Glu-Thr-Gly-COOH corresponding to the strong hydrophilic regions 37-42 and 83-88, respectively, on ribonuclease A were synthesized by solid-phase method. These synthetic peptides showed antigenic characteristics and provided an experimental validity to the prediction made earlier, supporting the view that highly hydrophilic regions on the protein have a good correlation with their being potentially antigenic.

A new ribonuclease from cobra venom (Naja naja) showing specificity towards cytidylic acid

A ribonuclease was isolated and purified to homogeneity from cobra venom. The enzyme was found to be homogeneous on SDS and non-SDS polyacrylamide gel electrophoreses, and high performance liquid chromatography. The purified enzyme hydrolysed poly(rC), but not poly(rA), poly(rU), poly(rG), poly(rI), or poly(rI).poly(rC). The presence of magnesium was found to be an essential requirement for the nucleolytic activity of this enzyme.