O. Habuchi coauthored a 1982 study, with N. Miyashita, separating two positional sulfotransferase activities from chick embryo cartilage. The work experimentally distinguished chondroitin 4-sulfotransferase and chondroitin 6-sulfotransferase, which modify different positions in the same kind of carbohydrate backbone.[ref]
Separation and characterization of chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase from chick embryo cartilage by O. Habuchi and N. Miyashita. original byline and Abstract, positional activities
The separated preparations differed in their biochemical behavior. Under the reported comparison without sulfhydryl compounds, the 4-sulfotransferase activity was very low, whereas the 6-sulfotransferase activity was essentially unaffected.[ref]
This is useful evidence because an assay condition can change the contribution of different activities within a preparation. In a hypothetical mixture with two activities, observing a decline in total signal would not establish that both activities declined equally. Separating them and measuring each under matched conditions supplies more specific information.
The distinction also links reaction chemistry to the meaning of an enzyme assay. Chondroitin modification can vary in the number and location of attached groups, while protein abundance supplies another measurement. The credited study provides a concrete example of using separable properties to investigate how a family of related reactions is implemented.
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