Summary
The epithelial mucus ofRana pipiens is shown to be highly negative by histochemical procedures, uptake of tagged extracellular markers, equilibrium dialysis, and QAE-Sephadex G-25 ion exchange chromatography. The mucus is found to contain 0.4% (dry weight) sulfate, 16% (dry weight) protein and 9% (dry weight) neutral sugars, whereas no sialic acid is detected. A mucin charge of −40 equivalents mole−1 is calculated by equilibrium dialysis using a molecular mass of 100,000 Dalton. An independent determination of in situ charge density by radionuclide uptake onto the frog surface (1.55 meq l−1) suggests that this estimate of mucin charge is correct. Based on analysis of size-exclusion chromatography fractions, it is suggested that mucus contains a sulfated glyco-protein (100,000 Dalton) that forms aggregates of about one million Dalton.
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Stith, B.J. Biochemical examination ofRana pipiens epithelial mucus. J Comp Physiol B 155, 89–96 (1984). https://doi.org/10.1007/BF00688796
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DOI: https://doi.org/10.1007/BF00688796