title: Rational design, synthesis and evaluation of first generation inhibitors of the Giardia lamblia fructose-1,6-biphosphate aldolase.
abstract: Inhibitors of the Giardia lamblia fructose 1,6-bisphosphate aldolase (GlFBPA), which transforms fructose 1,6-bisphosphate (FBP) to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, were designed based on 3-hydroxy-2-pyridone and 1,2-dihydroxypyridine scaffolds that position two negatively charged tetrahedral groups for interaction with substrate phosphate binding residues, a hydrogen bond donor to the catalytic Asp83, and a Zn(2+) binding group. The inhibition activities for the GlFBPA catalyzed reaction of FBP of the prepared alkyl phosphonate/phosphate substituted 3-hydroxy-2-pyridinones and a dihydroxypyridine were determined. The 3-hydroxy-2-pyridone inhibitor 8 was found to bind to GlFBPA with an affinity (K(i)=14μM) that is comparable to that of FBP (K(m)=2μM) or its inert analog TBP (K(i)=1μM). The X-ray structure of the GlFBPA-inhibitor 8 complex (2.3Å) shows that 8 binds to the active site in the manner predicted by in silico docking with the exception of coordination with Zn(2+). The observed distances and orientation of the pyridone ring O=C-C-OH relative to Zn(2+) are not consistent with a strong interaction. To determine if Zn(2+)coordination occurs in the GlFBPA-inhibitor 8 complex in solution, EXAFS spectra were measured. A four coordinate geometry comprised of the three enzyme histidine ligands and an oxygen atom from the pyridone ring O=C-C-OH was indicated. Analysis of the Zn(2+) coordination geometries in recently reported structures of class II FBPAs suggests that strong Zn(2+) coordination is reserved for the enediolate-like transition state, accounting for minimal contribution of Zn(2+) coordination to binding of 8 to GlFBPA.
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Li
authors.forename: Zhengang
authors.initials: Z
authors.lastname: Liu
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Cho
authors.forename: Jiwen
authors.initials: J
authors.lastname: Zou
authors.forename: Maozhen
authors.initials: M
authors.lastname: Gong
authors.forename: Robert M
authors.initials: RM
authors.lastname: Breece
authors.forename: Andrey
authors.initials: A
authors.lastname: Galkin
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Gabriel D
authors.initials: GD
authors.lastname: Maestas
authors.forename: David L
authors.initials: DL
authors.lastname: Tierney
authors.forename: Osnat
authors.initials: O
authors.lastname: Herzberg
authors.forename: Debra
authors.initials: D
authors.lastname: Dunaway-Mariano
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Mariano
mesh_terms: D000818:Animals; D001665:Binding Sites; D004099:Dihydroxyacetone Phosphate / Q000737:chemistry / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry; D005634:Fructose-Bisphosphate Aldolase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D016829:Giardia lamblia / Q000201:enzymology*; D007700:Kinetics; D008024:Ligands; D015032:Zinc / Q000737:chemistry
chemical_list: D004791:Enzyme Inhibitors; D008024:Ligands; D004099:Dihydroxyacetone Phosphate; D005634:Fructose-Bisphosphate Aldolase; D015032:Zinc