title: Cyclic peptide unguisin A is an anion receptor with high affinity for phosphate and pyrophosphate.
abstract: Unguisin A (1) is a marine-derived, GABA-containing cyclic heptapeptide. The biological function of this flexible macrocycle is obscure. Here we show that compound 1 lacks any detectable activity in antimicrobial growth inhibition assays, a result that runs contrary to a previous report. However, we find that 1 functions as a promiscuous host molecule in a variety of anion-binding interactions, with high affinity particularly for phosphate and pyrophosphate. We also show that a series of rigidified, backbone-fluorinated analogues of 1 displays altered affinity for chloride ions.
authors.affiliation: School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia. p.thordarson@unsw.edu.au l.hunter@unsw.edu.au.
authors.forename: A
authors.initials: A
authors.lastname: Daryl Ariawan
authors.affiliation: School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia. p.thordarson@unsw.edu.au l.hunter@unsw.edu.au and Australian Centre for Nanomedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: James E A
authors.initials: JE
authors.lastname: Webb
authors.affiliation: School of Chemistry, The University of Sydney, NSW 2006, Australia.
authors.forename: Ethan N W
authors.initials: EN
authors.lastname: Howe
authors.affiliation: School of Chemistry, The University of Sydney, NSW 2006, Australia.
authors.forename: Philip A
authors.identifier: http://orcid.org/0000-0001-9751-4910
authors.initials: PA
authors.lastname: Gale
authors.affiliation: School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia. p.thordarson@unsw.edu.au l.hunter@unsw.edu.au and Australian Centre for Nanomedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Pall
authors.identifier: http://orcid.org/0000-0002-1200-8814
authors.initials: P
authors.lastname: Thordarson
authors.affiliation: School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia. p.thordarson@unsw.edu.au l.hunter@unsw.edu.au.
authors.forename: Luke
authors.identifier: http://orcid.org/0000-0002-8678-3602
authors.initials: L
authors.lastname: Hunter
mesh_terms: D011756:Diphosphates / Q000737:chemistry*; D008958:Models, Molecular; D010456:Peptides, Cyclic / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D011756:Diphosphates; D010456:Peptides, Cyclic; D010710:Phosphates; C561693:unguisin A; C107241:diphosphoric acid