Improved Method for the Purification of Biologically Active Transcobalamin II

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Abstract
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 (J. Biol. Chem. 247, 7709–7717 (1972)). The simplified method incorporated isoelectric precipitation of the TC II into the purification scheme which permitted the elimination of two colimn chromatographic steps originally reported by the above worke-s. The final preparation had 26.7 jjg of vitamin B, ∼ (B12) bound per 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 lleLa cells in tissue culture.