Selective hydrolysis of oxidized insulin chain B by a Zr(IV)-substituted Wells-Dawson polyoxometalate
| Autor: | Annelies Sap, Tatjana N. Parac-Vogt, Gregory Absillis |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Circular dichroism
Aqueous solution Magnetic Resonance Spectroscopy Chemistry Circular Dichroism Hydrolysis Inorganic chemistry Nuclear magnetic resonance spectroscopy Tungsten Compounds Mass Spectrometry Inorganic Chemistry Crystallography Polyoxometalate Side chain Proton NMR Peptide bond Insulin Zirconium Oxidation-Reduction Chromatography High Pressure Liquid |
| Zdroj: | Dalton transactions (Cambridge, England : 2003). 44(4) |
| ISSN: | 1477-9234 |
| Popis: | We report for the first time on the selective hydrolysis of a polypeptide system by a metal-substituted polyoxometalate (POM). Oxidized insulin chain B, a 30 amino acid polypeptide, was selectively cleaved by the Zr(IV)-substituted Wells–Dawson POM, K15H[Zr(α2-P2W17O61)2]·25H2O, under physiological pH and temperature conditions in aqueous solution. HPLC-ESI-MS, LC-MS/MS, MALDI-TOF and MALDI-TOF MS/MS data indicate hydrolysis at the Phe1–Val2, Gln4–His5, Leu6–Cys(SO3H)7, and Gly8–Ser9 peptide bonds. The rate of oxidized insulin chain B hydrolysis (0.45 h−1 at pH 7.0 and 60 °C) was calculated by fitting the integration values of its HPLC-UV signal to a first-order exponential decay function. 1H NMR measurements show significant line broadening and shifting of the polypeptide resonances upon addition of the Zr(IV)-POM, indicating that interaction between the Zr(IV)-POM and the polypeptide takes place in solution. Circular dichroism (CD) measurements clearly prove that the flexible unfolded nature of the polypeptide was retained in the presence of the Zr(IV)-POM. The thermal stability of the Zr(IV)-POM in the presence of the polypeptide chain during the hydrolytic reaction was confirmed by 31P NMR spectroscopy. Despite the highly negative charge of the Zr(IV)-POM, the mechanism of interaction appears to be dominated by a strong metal-directed binding between the positively charged Zr(IV) center and negatively charged amino acid side chains. ispartof: Dalton Transactions vol:44 issue:4 pages:1539-1548 ispartof: location:England status: published |
| Databáze: | OpenAIRE |
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