Development of novel organometallic sulfonamides with N-ethyl or N-methyl benzenesulfonamide units as potential human carbonic anhydrase I, II, IX and XII isoforms' inhibitors: Synthesis, biological evaluation and docking studies.

In the search of new cymantrenyl- and ferrocenyl-sulfonamides as potencial inhibitors of human carbonic anhydrases (hCAs), four compounds based on N-ethyl or N-methyl benzenesulfonamide units have been obtained. These cymantrenyl (1a-b) and ferrocenyl (2a-b) derivatives were prepared by the reaction between aminobenzene sulfonamides ([NH2-(CH2)n-(C6H4)-SO2-NH2)], where n = 1, 2) with cymantrenyl sulfonyl chloride (P1) or ferrocenyl sulfonyl chloride (P2), respectively. All compounds were characterized by conventional spectroscopic techniques and cyclic voltammetry. In the solid state, the molecular structures of compounds 1a, 1b, and 2b were determined by single-crystal X-ray diffraction. Biological evaluation as carbonic anhydrases inhibitors were carried out and showed derivatives 1b y 2b present a higher inhibition than the drug control for the Human Carbonic Anhydrase (hCA) II and IX isoforms (KI = 7.3 nM and 5.8 nM, respectively) and behave as selective inhibition for hCA II isoform. Finally, the docking studies confirmed they share the same binding site and interactions as the known inhibitors acetazolamide (AAZ) and agree with biological studies.

Imidate-based cross-linkers for structural proteomics: increased charge of protein and peptide ions and CID and ECD fragmentation studies.

Chemical cross-linking is an attractive low-resolution technique for structural studies of protein complexes. Distance constraints obtained from cross-linked peptides identified by mass spectrometry (MS) are used to construct and validate protein models. Amidinating cross-linkers such as diethyl suberthioimidate (DEST) have been used successfully in chemical cross-linking experiments. In this work, the application of a commercial diimidate cross-linking reagent, dimethyl suberimidate (DMS), was evaluated with model peptides and proteins. The peptides were designed with acetylated N-termini followed by random sequences containing two Lys residues separated by an Arg residue. After cross-linking reactions, intra- and intermolecular cross-linked species were submitted to CID and ECD dissociations to study their fragmentation features in the gas phase. Fragmentation of intramolecular peptides by collision induced dissociation (CID) demonstrates a unique two-step fragmentation pathway involving formation of a ketimine as intermediate. Electron capture and electron transfer dissociation (ECD and ETD) experiments demonstrated that the cyclic moiety is not dissociated. Intermolecular species demonstrated previously described fragmentation behavior in both CID and ECD experiments. The charge state distributions (CSD) obtained after reaction with DMS were compared with those obtained with disuccinimidyl suberate (DSS). CSDs for peptides and proteins were increased after their reaction with DMS, owing to the higher basicity of DMS modified species. These features were also observed in LC-MS experiments with bovine carbonic anhydrase II (BCA) after cross-linking with DMS and tryptic proteolysis. Cross-linked peptides derived from this protein were identified at high confidence and those species were in agreement with the crystal structure of BCA.

Affinity of sulfamates and sulfamides to carbonic anhydrase II isoform: experimental and molecular modeling approaches.

Sixteen aromatic and aliphatic sulfamides and sulfamates were synthesized and tested in their inhibition to carbonic anhydrase CAII activity. The weaker inhibition pattern shown by sulfamides as compared to sulfamates is interpreted in this research by means of molecular modeling techniques, including known inhibitors (topiramate and its sulfamide cognate) in the analysis. The results nicely explain the origin of the inhibitory activity, which is not only related to positive interactions of the ligand with the active site residues but also to the solvation pattern characteristic of each ligand.

Recombinant plant gamma carbonic anhydrase homotrimers bind inorganic carbon.

Gamma carbonic anhydrases (gammaCA) are widespread in Prokaryotes. In Eukaryotes, homologous genes were found only in plant genomes. In Arabidopsis and maize, the corresponding gene products are subunits of mitochondrial Complex I. At present, only gammaCA homotrimers of Methanosarcina thermophila (CAM) show reversible carbon dioxide (CO(2)) hydration activity. In the present work, it is shown that recombinant plant gammaCA2 could form homotrimers and bind H(14)CO(3)(-). However, they are unable to catalyse the reversible hydration of CO(2). These results suggest that plant gammaCAs do not act as carbonic anhydrases but with a related activity possibly contributing to recycle CO(2) in the context of photorespiration.