Quantitative microspectrometrical determination of the total protein and total protein-SH content of the nuclei of Ehrlich ascites tumor cells without prior isolation.

The total protein and total protein-SH content of both the cytoplasmic fraction and the nuclei of Ehrlich ascites tumor cells (EATC) were determined macroscopically and microspectrometrically. The separation into cytoplasmic and nuclear fraction was performed by a modification of the method of Mamaril et al. [4]. The macroscopical determination of the total protein and the total protein-SH content were performed with the Folin method of Lowry et al. [2] and the DTNB method of Ellman [1], respectively. The quantitative microspectrometrical determinations of total protein content and of total protein-SH content were performed using the tetrazonium staining method of Nöhammer [5] and Nöhammer et al. [6] and the mercurochromcyanide (MCN) method of Nöhammer et al. [7], respectively. Within the intact cells, fixed and stained histochemically, the total protein and the total protein-SH content of the nuclei were determined microspectrometrically. The so called "nuclear extinctions", measured as the sum of the extinctions of the nucleus and of the parts of the cytoplasm above and below the nucleus, were calculated into the true nuclear extinctions, which then show a good correspondence to the values measured both microspectrometrically and macroscopically on isolated nuclei. The calculation for the true nuclear extinctions is based on a special preparation of spherically shaped cells and nuclei.