title: X-ray absorption spectroscopic investigation of the resting ferrous and cosubstrate-bound active sites of phenylalanine hydroxylase.
abstract: Previous studies of ferrous wild-type phenylalanine hydroxylase, [Fe(2+)]PAH(T)[], have shown the active site to be a six-coordinate distorted octahedral site. After the substrate and cofactor bind to the enzyme ([Fe(2+)]PAH(R)[L-Phe,5-deaza-6-MPH(4)]), the active site converts to a five-coordinate square pyramidal structure in which the identity of the missing ligand had not been previously determined. X-ray absorption spectroscopy (XAS) at the Fe K-edge further supports this coordination number change with the binding of both cosubstrates to the enzyme, and determines this to be due to the loss of a water ligand.
authors: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors: Erik C
authors: EC
authors: Wasinger
authors: Natasa
authors: N
authors: Mitić
authors: Britt
authors: B
authors: Hedman
authors: John
authors: J
authors: Caradonna
authors: Edward I
authors: EI
authors: Solomon
authors: Keith O
authors: KO
authors: Hodgson
mesh_terms: D000818:Animals; D001665:Binding Sites; D003460:Crystallization; D005296:Ferrous Compounds / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D010084:Oxidation-Reduction; D010651:Phenylalanine Hydroxylase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D013057:Spectrum Analysis / Q000379:methods; D013379:Substrate Specificity; D014867:Water / Q000737:chemistry; D014965:X-Rays
chemical_list: D005296:Ferrous Compounds; D008024:Ligands; D014867:Water; D010651:Phenylalanine Hydroxylase