A Spectrophotometric Assay for Measuring the Uptake of Actinobolin by Components of Human Enamel 1

Summary A spectrophotometric assay was developed for measuring the uptake of the antibiotic actinobolin by hydroxylapatite (HAP) or powdered human enamel. The assay is sufficiently sensitive to detect <2.0 μg actinobolin/ml of: 0.01 M sodium phosphate buffer at pH 5.5, 7.0, or 8.0; deionized water; deionized water containing 1% salivary supernatant; or each of the above indicated solvent systems containing 1-5 parts per million sodium fluoride. The utility of the assay system has been demonstrated by data which show that approximately 5-7 μg of actinobolin are bound per 10 mg of HAP or powdered enamel. The assistance of Fran Hardy is gratefully acknowledged. Thanks are extended to Henry Dion (Parke, Davis & Co.) for generous supplies of actinobolin.