The chemical composition of calf thymus nucleoprotein

Analyses have been made of the ratios of arginine and lysine to phosphorus in a number of DNP preparations from individual beef thymus glands. After dialysis constant values of these ratios were obtained, which support the concept of a definite nucleoprotein molecule rather than a loose association of histone and DNA. The total amount of basic amino acids (including histidine) is only sufficient to neutralize about 90% of the total phosphate present. When account is taken of the acidic amino acids, the sodium content of the preparations corresponds to the uncombined phosphate groups. The metachromasy observed in the presence of toluidine blue indicates that the uncombined phosphate groups occur in sequences.