NDLI: Selective hydrolysis of oxidized insulin chain B by a Zr(IV)-substituted Wells

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Sap, Annelies Absillis, Gregory Parac-vogt, Tatjana N.
Description	Author Affiliation: Sap A ( KU Leuven, Department of Chemistry, Celestijnenlaan 200F, B-3001 Heverlee, Belgium. tatjana.vogt@chem.kuleuven.be.)
Abstract	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, $K_{15}H[Zr(α_{2}-P_{2}W_{17}O_{61})_{2}]·25H_{2}O,$ 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, $Leu6–Cys(SO_{3}H)7,$ 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. $^{1}H$ 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 $^{31}P$ 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.
ISSN	14779226
Issue Number	4
Volume Number	44
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-01-28
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Insulin Chemistry Tungsten Compounds Zirconium Chromatography, High Pressure Liquid Circular Dichroism Hydrolysis Magnetic Resonance Spectroscopy Mass Spectrometry Methods Oxidation-Reduction Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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