Comparison of DNase, DNA-polymerase and RNA-polymerase activities present in the DNA-binding proteins of normal human dermis, epidermis, horny layer and psoriatic scales.

DNA-binding proteins (DBP) of normal human dermis, epidermis, horny layer and psoriatic scales represent a tissue-specific group of mostly nuclear nonhistone proteins. To analyse their function, the different DBP fractions were examined concerning the presence of DNase, DNA-polymerase and RNA-polymerase activities. DBP of normal epidermis and horny layer contain four different DNases. One DNase of both DBP fractions is active only at pH 5.0. Three DNases of epidermal DBP are active at a pH-range from 5.0--8.5, while the corresponding DNases of horny layer-DBP are most active at pH 7.4. Probably these DNases have changed their pH-optimum during keratinisation. DBP of psoriatic scales include no activity of these three DNases and the pH 5.0-DNases seem to have reduced DNA-affinity. Human dermis DBP contain quite another set of four DNases which hardly can be correlated to the DNases of epidermal DBP. DNA-polymerase activities are present in each fraction and derive from different DNA-polymerases. Two DNA-polymerases with pI-values of 4.5 and 9.3 may correspond to beta- and alpha-DNA-polymerase of eukaryotes, respectively. Further activity of proteins which are focussed at pH 6.5--7.2 and 8.2 could be detected. The proteins represent either tissue-specific DNA-polymerases or further thymidine monophosphate incorporating enzymes. Contrary, RNA-polymerase activity could not be enriched from correlating extracts by DNA-cellulose chromatography.