{'fraction_non_alphanumeric': 0.022105263157894735, 'fraction_numerical': 0.00631578947368421, 'mean_word_length': 5.891304347826087, '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}}
Gel electrophoretic separation of transcription complexes: an assay for RNA polymerase selectivity and a method for promoter mapping.

We describe a method for analyzing ternary transcription complexes, of RNA polymerase, DNA and nascent RNA32 chains, by agarose gel electrophoresis. When the RNA of such complexes is 32P-labelled, a simple comparison of the DNA fluorogram with an autoradiogram identifies transcriptionally active DNA molecules and restriction fragments in any mixture. Two limitations on the method are described: 1) retardation during electrophoresis of polymerase-DNA complexes relative to their conjugate bare NA fragments; 2) failure of very large ternary complexes to enter gels. The following potential applications of the method are surveyed: transcription unit (elongation) mapping, separation of RNA molecules in a mixture of transcripts, dinucleotide primer mapping and identification of preferred template conformations.