6gnl

Publication Abstract from PubMed

The successful cocrystallization of the noncovalent complex formed between (Et2NH2)8[{alpha-PW11O39Zr-(mu-OH)(H2O)}2].7H2O Keggin polyoxometalate (2) and Hen Egg White Lysozyme (HEWL) protein is reported. The resulting structural model revealed interaction between monomeric [Zr(PW11O39)](4-)(1), which is a postulated catalytically active species, and the protein in two positions in the asymmetric unit. The first position (occupancy 36%) confirms the previously observed binding sites on the protein surface, whereas the second position (occupancy 14%) provides novel insights into the hydrolytic mechanisms of Zr(IV)-substituted polyoxometalates. The new interaction site occurs at the Asn65 residue, which is directly next to the Asp66-Gly67 peptide bond that was identified recently as a cleavage site in the polyoxometalate-catalysed hydrolysis of HEWL. Furthermore, in this newly discovered binding site, the monomeric polyoxometalate 1 is observed to bind directly to the side chain of the Asn65 residue. This binding of Zr(IV) as a Lewis-acid metal to the carbonyl O atom of the Asn65 side chain is very similar to the intermediate state proposed in density functional theory (DFT) studies in which Zr(IV) activates the peptide bond via interaction with its carbonyl O atom, and can be thus regarded as a model for interaction between Zr(IV) and a peptide bond.

Direct observation of the Zr(IV) interaction with the carboxamide bond in a noncovalent complex between Hen Egg White Lysozyme and a Zr-substituted Keggin polyoxometalate.,Vandebroek L, Van Meervelt L, Parac-Vogt TN Acta Crystallogr C Struct Chem. 2018 Nov 1;74(Pt 11):1348-1354. doi:, 10.1107/S2053229618010690. Epub 2018 Oct 19. PMID:30398187^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.