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The expression survey is messenger RNA rather than protein, and the enzyme is heterologously expressed.\nexposure: Recombinant PDE9A1 against 3-isobutyl-1-methylxanthine, sildenafil and SCH51866\nevidence_span: {\"source_cache\": \"artifacts/sildenafil-research/9624145.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"ea6afcfbb102bf5a407894b06969c9fe245261fa8a1fea8fb92b201d8b24ace2\", \"start_char\": 0, \"end_char\": 1265, \"text_sha256\": \"ea6afcfbb102bf5a407894b06969c9fe245261fa8a1fea8fb92b201d8b24ace2\"}\n[sil-p9624145] Identification and characterization of a novel family of cyclic nucleotide phosphodiesterases. 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