Affinity difference of adenosine deaminases for the purine riboside-epoxyactivated Sepharose 6B column

The small-size adenosine deaminase (Mr = 35,000 and 43,000) in calf intestinal mucosa, frog liver and scallop adductor muscle and the large-size deaminase (Mr = 100,000) in frog liver probably formed by adding a conversion protein to the small enzyme, were tightly bound to the purine riboside affinity column. Binding of the other large-size enzymes (Mr = 140,000) in the midgut gland of scallop and mussel to the column was not successful. It seems that the binding difference does not depend on a change in affinity between active site and ligand but rather on the stereospecific positioning of active site in the enzyme molecules.