This manual synthesis records directly inspected structural evidence. A separate completed Falcon report supplies gene-level literature context.
Current FlyBase lists E8NH57 as the native 178-residue Hn-PD product. It matches full-length fly P17276 residues 275–452 exactly. The three annotated iron ligands remain, while the ACT regulatory domain and a substantial part of the catalytic domain are absent. See reproducible analysis, with source JSON, alignments and self-controls.
PMID:10694386(https://pubmed.ncbi.nlm.nih.gov/10694386/) describes the human PAH catalytic domain, pterin positioning and mutagenesis of Phe254 and Glu286. PMID:12126628(https://pubmed.ncbi.nlm.nih.gov/12126628/) identifies substrate-responsive movement of the 131–155 loop. Mapping these documented sites first to full-length Hn and then to PD shows loss of that loop, the pterin-binding 245–250 region and the Phe254 counterpart. The full-length Hn positive control retains these features. Only 149 of 307 human catalytic-domain positions align to PD. Both primary abstracts were read and are cached; mechanistic positions and mapping outputs are explicit files.
PMID:9434741(https://pubmed.ncbi.nlm.nih.gov/9434741/) concerns an active PAH construct retaining the C-terminal 336 residues. That result does not establish activity of a much shorter 178-residue product; the actual missing reaction-center architecture provides the stronger reason to reject activity transfer.
Conventional pteridine-dependent hydroxylase activity is refuted for the exact PD product. Retained iron ligands do not replace missing substrate/cofactor geometry. A noncatalytic or regulatory contribution to aromatic amino acid metabolism remains unresolved. Full-length Henna enzyme biology and the validity of the native PD transcript model are separate questions.