{'fraction_non_alphanumeric': 0.02613065326633166, 'fraction_numerical': 0.027135678391959798, 'mean_word_length': 4.724137931034483, '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}}
Cytochrome P450: the active oxidant and its spectrum.

This Forum focuses on the nature of the elusive oxidizing intermediate in P450 catalysis. The identity of this species has reemerged as a topic of contentious debate. It was recently reported that laser flash photolysis (LFP) can be used to generate P450 compound I (P450-I) quantitatively. Kinetic analyses of the reaction of the LFP-generated intermediate with substrates have been suggested to indicate that compound I is not the active oxidant in P450 catalysis. We evaluate these claims via an analysis of the UV/visible spectrum of the LFP-generated intermediate. The techniques of singular value decomposition and target testing are used to obtain the spectrum of P450-I in a model-independent manner from stopped-flow data of the reaction of P450 with m-chloroperbenzoic acid. It is shown that the LFP-generated spectrum bears no similarity to the P450-I spectrum. One may conclude that the LFP-generated intermediate is not P450-I.