{'fraction_non_alphanumeric': 0.023972602739726026, 'fraction_numerical': 0.0273972602739726, 'mean_word_length': 5.088541666666667, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Studies on Seryl and Phenyl-alanyl Synthetases from Ascitic Tumor Cells Treated with 20-Methylcholanthrene

Summary The aminoacylation of tRNA is an important step in the regulation of protein synthesis. The aminoacyl-tRNA synthetases may have a regulatory function in the transformation of normal cells to neoplastic cells. Seryl and phenylalanyl synthetase have been isolated from ascitic tumor cells which were previously treated with 20-methyl-cholanthrene. The different steps of preparation are (NH4)2SO4 precipitation of the 105,000g supernatant (between 50 and 65% saturation), chromatography on DEAE cellulose, CM Sephadex C-50 and hydroxy-apatite. The purification fold of the seryl-tRNA synthetase was 450 times with the molecular weight of 120,000. The present studies have shown that the K m for serine was about 20 times higher in MCA-treated cells than in the controls, while the K m for ATP was only increased 3–4 times. These values indicate that the synthetases possibly have a regulatory role in the protein synthesis of the cancer cells with and without treatment with MCA. Similar differences were not found in the case of phenylalanyl synthetase.