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Carbonic anhydrase isoform XIV (CA XIV) is the last member of the human (h) CA family discovered so far, being localized in brain, kidneys, colon, small intestine, urinary bladder, liver, and spinal cord. It has recently been described as a possible drug target for treatment of epilepsy, some retinopathies as well as some skin tumors. Human carbonic anhydrase (hCA) XIV is a membrane-associated protein consisting of an N-terminal extracellular domain, a putative transmembrane region, and a small cytoplasmic tail. In this article, we report the expression, purification, and the crystallographic structure of the entire extracellular domain of this enzyme. The analysis of the structure revealed the typical α-CA fold, in which a 10-stranded β-sheet forms the core of the molecule, while the comparison with all the other membrane associated isoforms (hCAs IV, IX, and XII) allowed to identify the diverse oligomeric arrangement and the sequence and structural differences observed in the region 127-136 as the main factors to consider in the design of selective inhibitors for each one of the membrane associated α-CAs., (Copyright © 2013 Wiley Periodicals, Inc.)

The potential of carbonic anhydrase (CA) family as target for the drug design of inhibitors with various medicinal chemistry applications has been recognized from long time, whereas the industrial interest in using these enzymes as biocatalysts for carbon dioxide sequestration and biofuel production is only recently emerging. However, an efficient utilization in these processes often requires stable enzymes, able to work in the harsh conditions typical of the CO2 capture process. In this context CAs active at very high temperatures are of extreme interest. In this chapter we have summarized in a comparative manner all existing data on thermostable CAs both isolated by extremophiles and obtained by protein engineering studies. Among the five CA-classes, the biochemical and structural features of thermostable α-, β- and γ-CAs have been discussed. Data show that so far α-CAs isolated from thermophilic organisms are the best candidates to be used in biotechnological processes, even if plenty of work can be still done in this field also with help of protein engineering.

Introduction: Carbonic anhydrases (CAs, EC 4.2.1.1) exist as five genetically distinct families (α, β, γ, δ and ζ) in organisms all over the phylogenetic tree. Due to the ubiquity of such enzymes, the selective inhibition and polypharmacology of inhibitors is an important aspect of all drug design campaigns. There are several classes of CA inhibitors (CAIs): i) metal ion binders (sulfonamides and their isosteres [sulfamates/sulfamides], dithiocarbamates, mercaptans and hydroxamates); ii) compounds anchoring to the zinc-coordinated water molecule/hydroxide ion (phenols, carboxylates, polyamines, esters and sulfocoumarins) and iii) coumarins and related compounds which apparently bind even further away from the metal ion., Areas Covered: The authors rationalize the drug design strategies of inhibitors belonging to the first two classes, based on recent X-ray crystallographic data. More precisely, this is achieved by analyzing how the hydrophobic and hydrophilic halves of the enzyme active site interact with inhibitors. This task has been eased by the recent report of β-CA-like enzymes possessing carbon disulfide and carbonyl sulfide hydrolase activities, respectively, allowing the authors to propose a general approach of structure-based drug design of CAIs., Expert Opinion: Although amazing progress has been made in the structure-based drug design of CAIs, this field is still in progress, with many constantly emerging new findings. Indeed, several new such enzymes were discovered and characterized recently and novel chemotypes were explored for finding compounds with a better inhibition profile. It is anticipated that this will continue to be one of the main frontiers in the search of pharmacologically relevant enzyme inhibitors.