Abstract
Studies were carried out on the preparation of a vitamin B_<12>-bound adsorbent suitable for purifying CH_3-B_<12>-dependent enzyme by affinity chromatography. The results obtained were as follows: 1) Several B_<12> derivatives modified in the upper ligand were synthesized to examine their affinities with apo-methionine synthetase from Escherichia coli. Carboxypropyl-B_<12> was chosen as the ligand of the adsorbent, judging from its sufficient affinity to the apo-enzyme, the activation of the inactive enzyme complex by photolysis and slight non-specific interaction of the upper ligand moiety with apoenzyme. 2) Aminobutyl group was bound to Sepharose as the spacer, since spacer should not interact with the enzyme protein non-specifically and must keep an appropriate distance between the ligand and the carrier. 3) The ligand and the spacer-carrier chosen as above were coupled with a water-soluble carbodiimide to get an affinity adsorbent having the structure of Sepharose-(CH_2)_4-NHCO-(CH_2)_3-B_<12>. 4) B_<12>-dependent methionine synthetase from E. coli was highly purified with a good yield in only one step by the affinity chromatography on this B_<12>-bound Sepharose.
