| Autor: |
Joseph Nr, Milton B. Engel |
| Rok vydání: |
1959 |
| Předmět: |
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| Zdroj: |
Archives of Biochemistry and Biophysics. 85:209-224 |
| ISSN: |
0003-9861 |
| DOI: |
10.1016/0003-9861(59)90464-3 |
| Popis: |
By studying colloidal charge density at various pH levels, titration curves of the surface of human epidermis were determined. Normal Donnan potentials were measured and the Donnan ratios estimated. Colloidal charge densities were calculated from Donnan ratios. Displaced Donnan potentials were measured by replacing an isotonic saline solution by a one-tenth dilution at any pH. These potentials depend on the ionic conductances as well as on the Donnan ratios. Theoretical calculations from observed Donnan potentials and standard values of ionic conductances gave values in agreement with the experiments. The potentials and titration curves were independent of the location of the reference junction. At low pH, epidermis was found to have a positive charge of about 0.15 equiv./kg. water. At pH 7.4, the charge was of the same magnitude but negative. The isoelectric point was found to be near pH 4.5. Approximately half the acid-binding groups were found between pH 2.2 and 2.9. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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