Promiscuity of carbonic anhydrase II: Unexpected ester hydrolysis of carbohydrate-based sulfamate inhibitors

Lopez, Marie, Vu. Hoan, Wang, Conan K., Wolf, Maarten G., Groenhof, Gerrit, Innocentis, Alessio, Supuran, Claudiu T. and Poulsen, Sally-Ann (2011) Promiscuity of carbonic anhydrase II: Unexpected ester hydrolysis of carbohydrate-based sulfamate inhibitors. Journal of The American Chemical Society, 133 45: 18452-18462. doi:10.1021/ja207855c

Author Lopez, Marie
Vu. Hoan
Wang, Conan K.
Wolf, Maarten G.
Groenhof, Gerrit
Innocentis, Alessio
Supuran, Claudiu T.
Poulsen, Sally-Ann
Title Promiscuity of carbonic anhydrase II: Unexpected ester hydrolysis of carbohydrate-based sulfamate inhibitors
Journal name Journal of The American Chemical Society   Check publisher's open access policy
ISSN 0002-7863
Publication date 2011-11-16
Sub-type Article (original research)
DOI 10.1021/ja207855c
Volume 133
Issue 45
Start page 18452
End page 18462
Total pages 11
Place of publication Washington, DC, U.S.A.
Publisher American Chemical Society
Collection year 2012
Language eng
Formatted abstract
Carbonic anhydrases (CAs) are enzymes whose endogenous reaction is the reversible hydration of CO2 to give HCO3 and a proton. CA are also known to exhibit weak and promiscuous esterase activity toward activated esters. Here, we report a series of findings obtained with a set of CA inhibitors that showed quite unexpectedly that the compounds were both inhibitors of CO2 hydration and substrates for the esterase activity of CA. The compounds comprised a monosaccharide core with the C-6 primary hydroxyl group derivatized as a sulfamate (for CA recognition). The remaining four sugar hydroxyl groups were acylated. Using protein X-ray crystallography, the crystal structures of human CA II in complex with four of the sulfamate inhibitors were obtained. As expected, the four structures displayed the canonical CA protein–sulfamate interactions. Unexpectedly, a free hydroxyl group was observed at the anomeric center (C-1) rather than the parent C-1 acyl group. In addition, this hydroxyl group is observed axial to the carbohydrate ring while in the parent structure it is equatorial. A mechanism is proposed that accounts for this inversion of stereochemistry. For three of the inhibitors, the acyl groups at C-2 or at C-2 and C-3 were also absent with hydroxyl groups observed in their place and retention of stereochemistry. With the use of electrospray ionization–Fourier transform ion cyclotron resonance–mass spectrometry (ESI–FTICR–MS), we observed directly the sequential loss of all four acyl groups from one of the carbohydrate-based sulfamates. For this compound, the inhibitor and substrate binding mode were further analyzed using free energy calculations. These calculations suggested that the parent compound binds almost exclusively as a substrate. To conclude, we have demonstrated that acylated carbohydrate-based sulfamates are simultaneously inhibitor and substrate of human CA II. Our results suggest that, initially, the substrate binding mode dominates, but following hydrolysis, the ligand can also bind as a pure inhibitor thereby competing with the substrate binding mode.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ
Additional Notes Conan Wang was not affiliated with UQ at time of publication

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
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Created: Fri, 20 Jan 2012, 12:05:09 EST by Susan Allen on behalf of Institute for Molecular Bioscience