title: Interaction Study and Reactivity of Zr(IV) -Substituted Wells-Dawson Polyoxometalate towards Hydrolysis of Peptide Bonds in Surfactant Solutions.
abstract: The interaction between the 1:2 Zr(IV) :Wells-Dawson complex, K15 H[Zr(α2 -P2 W17 O61 )2] (1), and a range of surfactants was studied in detail with the aim of developing metal-substituted POMs as potential artificial proteases for membrane proteins. The surfactants include the positively charged cetyl(trimethyl)ammonium bromide (CTAB), the negatively charged sodium dodecyl sulfate (SDS), the neutral Triton X-100 (TX-100), and zwitterionic 3-[dodecyl(dimethyl)ammonio]-1-propanesulfonate (Zw3-13) and 3-[dimethyl(3-{[(3α,5β,7α,12α)-3,7,12-trihydroxy-24-oxocholan-24-yl]amino}propyl)ammonio]-1-propanesulfonate (CHAPS). A combination of multinuclear (1)H, (13)C, and (31) P NMR spectroscopy, (1)H diffusion-ordered NMR spectroscopy ((1)H DOSY), and nuclear Overhauser effect spectroscopy (NOESY) was used to examine the interaction between 1 and each surfactant on the molecular level. Cationic surfactant CTAB caused precipitation of 1 due to strong electrostatic interactions, while the anionic SDS and neutral TX-100 surfactants did not exhibit any interaction at neutral pD. (1)H DOSY NMR spectroscopy indicated an interaction between 1 and zwitterionic surfactants Zw3-12 and CHAPS, which occurs via the positively charged ammonium group in the surfactant molecule. In the presence of anionic, neutral, and zwitterionic surfactants, 1 preserves its catalytic activity towards the hydrolysis of the peptide bond in the dipeptide glycyl-l-histidine (GH). The fastest hydrolysis was observed at pD 7.0 and could be rationalized by taking into account pD-dependent speciation of 1 and coordination properties of GH.
authors.affiliation: Department Of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Quanten
authors.affiliation: NMR Laboratory, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bontchef Str., B1.9, Sofia, 1113, Bulgaria.
authors.forename: Pavletta
authors.initials: P
authors.lastname: Shestakova
authors.affiliation: Department Of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.
authors.forename: Dries
authors.initials: D
authors.lastname: Van Den Bulck
authors.affiliation: Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.
authors.forename: Christine
authors.initials: C
authors.lastname: Kirschhock
authors.affiliation: Department Of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium. tatjana.vogt@chem.kuleuven.be.
authors.forename: Tatjana N
authors.initials: TN
authors.lastname: Parac-Vogt
mesh_terms: D006860:Hydrogen Bonding; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D017830:Octoxynol / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D012996:Solutions / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry; D017973:Tungsten Compounds / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D017830:Octoxynol; D009942:Organometallic Compounds; D010455:Peptides; D012996:Solutions; D013501:Surface-Active Agents; D017973:Tungsten Compounds; D015040:Zirconium; C102296:polyoxometalate I; D000099294:Polyoxometalates
keywords: DOSY NMR; hydrolysis; peptide bonds; polyoxometalates; surfactants