. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. 8o J. BOOTH, E. BOYLAND VOL. 12 (1953) its comparatively high solubihty in purine solutions enabled measurements to be made over a wide range of concentrations. The effect of different concentrations of caffeine and deoxyribonucleic acid was investigated and an interesting difference observed. The molecular ratio decreased with increasing concentration in the case of caffeine and increased in the case of DNA. The solubilities were determined as b
. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. 8o J. BOOTH, E. BOYLAND VOL. 12 (1953) its comparatively high solubihty in purine solutions enabled measurements to be made over a wide range of concentrations. The effect of different concentrations of caffeine and deoxyribonucleic acid was investigated and an interesting difference observed. The molecular ratio decreased with increasing concentration in the case of caffeine and increased in the case of DNA. The solubilities were determined as before using caffeine concentrations ranging from M to M and sodium deoxyribonucleate concentrations equivalent to M to M nucleotide. The suspensions were shaken at 22° for i h since preliminary experiments had shown that there was no increase in solubility after this time. When measuring the concentration of dibenzacridine in the sodium deoxyribo- nucleate, it was necessary to add ml of 2 A^ NaOH to the filtrate on diluting, since 3001- 42 O e 1200 1 c o "6 o c 5 100. 1 2 3 Time (hours) Fig. 5. Effect of amount of 3 :4:5:6-dibenzcarbazole added on precipitation of the dibenzcarbazole- tetramethyluric acid complex, x X 200 mg/1 dibenzcarbazole in M tetramethyluric acid; # % 50 mg/1 dibenzcarbazole in M tetramethyluric acid. ionisation of the dibenzacridine occurred and the ion has a different absorption spectrum from the unionised molecule. The results are shown in Table II ( values for deoxy- ribonucleate are calculated as before). In the case of hydrocarbons dissolved in caffeine and tetramethyluric acid solutions studied by Weil-Malherbe^ the was either constant or decreased with increase in purine concentrations. Neish^, however, had observed that the for the solubility of 2-naphthylamine, 2-aminofluorene and benzidine in caffeine, increased with increase in caffeine concentration. Preparation of molecu
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