3T85

Human Carbonic Anhydrase II in complex with Acetylated Carbohydrate Sulfamates

Summary for 3T85

• Entry DOI: 10.2210/pdb3t85/pdb
• Related: 3T82 3T83 3T84
• Descriptor: Carbonic anhydrase 2, ZINC ION, 3,4-di-O-acetyl-6-O-sulfamoyl-alpha-D-mannopyranose, ... (4 entities in total)
• Functional Keywords: alpha carbonic anhydrase, lyase-lyase inhibitor complex, lyase/lyase inhibitor
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 29697.78

Authors

Hofmann, A.,Wang, C.K. (deposition date: 2011-08-01, release date: 2011-10-19, Last modification date: 2024-03-20)

Primary citation

Lopez, M.,Vu, H.,Wang, C.K.,Wolf, M.G.,Groenhof, G.,Innocenti, A.,Supuran, C.T.,Poulsen, S.A.
Promiscuity of carbonic anhydrase II. Unexpected ester hydrolysis of carbohydrate-based sulfamate inhibitors.
J.Am.Chem.Soc., 133:18452-18462, 2011

PubMed Abstract: Carbonic anhydrases (CAs) are enzymes whose endogenous reaction is the reversible hydration of CO(2) to give HCO(3)(-) 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 CO(2) 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.

PubMed: 21958118
DOI: 10.1021/ja207855c

Experimental method

X-RAY DIFFRACTION (2.4 Å)