L. Åberg coauthored a 1982 investigation of an enzyme involved in making dermatan sulfate. With A. Malmström, L. Åberg used an isotope labelling assay to follow hydrogen exchange during epimerization of residues in chondroitin.[ref]
The label was tritium attached at carbon five. Material released during incubation was distilled and quantified by liquid-scintillation counting. The study also compared conditions supporting the two epimerase activities present in microsome preparations.[ref]
Biosynthesis of dermatan sulphate. Assay and properties of the uronosyl C-5 epimerase by A. Malmström and L. Åberg. Abstract: isotope readout and different cofactor/pH requirements
The assay illustrates a distinction between a chemical event and the signal used to detect it. Radioactive counts report movement of a label under specified conditions; interpreting them as an enzyme activity requires an appropriate labelled substrate and comparisons for background release. Counting the signal alone would not identify which enzyme produced it.
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