PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 18346713-6 2008 The structure-activity analysis suggests that a small hydrophobic pocket and the H-loop of PDE5 are important for the inhibitor affinity, in addition to two common elements for binding of almost all the PDE inhibitors: the stack against the phenylalanine and the hydrogen bond with the invariant glutamine. Phenylalanine 241-254 phosphodiesterase 5A Homo sapiens 91-95