IMPROVED METHOD FOR PURIFICATION OF BIOLOGICALLY-ACTIVE TRANSCOBALAMIN-2

Transcobalamin II (TC II) was purified about 300,000-fold from Cohn fraction III using a modification of the procedure described by Allen and Majerus. The simplified method incorporated isoelectric precipitation of the TC II into the purification scheme which permitted the elimination of 2 column chromatographic steps in the original method. The final preparation had 26.7 .mu.g of vitamin B12 (B12) bound/mg of protein and an A280/A361 ratio of 2.05, both of which are in good agreement with the reported values. The purified TC II was biologically active with respect to its ability to facilitate penetration of B12 into HeLa cells in tissue culture.