Mechanistic Explanation of the Weak Carbonic Anhydrase's Esterase Activity.

In order to elucidate the elementary mechanism of the promiscuous esterase activity of human carbonic anhydrase (h-CA), we present an accurate theoretical investigation on the hydrolysis of fully-acetylated d-glucose functionalized as sulfamate. This h-CA's inhibitor is of potential relevance in cancer therapy. The study has been performed within the framework of three-layer ONIOM (QM-high:QM'-medium:MM-low) hybrid approach.

The in situ gas-phase formation of a C-glycoside ion obtained during electrospray ionization tandem mass spectrometry. A unique intramolecular mechanism involving an ion-molecule reaction.

Rationale: This study examines the electrospray ionization mass spectrometry (ESI-MS), in-source collision-induced dissociation (CID) fragmentation and low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) of a synthetic pair of β- and α-anomers of the amphiphilic cholesteryl polyethoxy neoglycolipids containing the 2-azido-2-deoxy-D-galactosyl-D-GalN3 moiety. We describe the novel and unique in situ gas-phase formation of a C-glycoside ion formed during all these gas-phase processes and propose a reasonable mechanism for its formation.

Methods: The synthetic amphiphilic glycolipids were composed of the 2-deoxy-2-azido-D-galactosyl moiety (GalN3, the hydrophilic part) covalently attached to a polyethoxy spacer which is covalently linked to the cholesteryl moiety (hydrophobic part).

Promiscuous ability of human carbonic anhydrase: QM and QM/MM investigation of carbon dioxide and carbodiimide hydration.

The hydration of carbodiimide, isoelectronic with carbon dioxide, mediated by human carbonic anhydrase (EC 4.2.1.