Fractionation of Indian cobra venom by column chromatography: I. Dextran gels

Abstract

Lyophilized Indian cobra venom ( Naja naja) was fractionated by gel filtration on columns of dextran polymers with three different degrees of cross-linkage. The eluants used were water, acetic and hydrochloric acid. The best resolution—five components—was obtained from the dextran gel with medium cross-linkage. Two of the components had toxic activity and were found to be heterogeneous by zone electrophoresis. Two of the nontoxic components appeared to contain nucleic acid. Several experimental parameters were tested; of these the ratio of gel volume to sample size was most critical. Highest yields and best resolution were obtained with minimal amounts of gel for a given amount of sample. This approach favored molecular-sieve action instead of adsorption. The use of mixed columns of two gels with different cross-linkage to utilize the selectivity in fractionation offered by each was not successful. Successive fractionations from the same column were not as reproducible as those from freshyl packed columns.