Switching the Inhibitor‐Enzyme Recognition Profile via Chimeric Carbonic Anhydrase XII

A key part of the optimization of small molecules in pharmaceutical inhibitor development is to vary the molecular design to enhance complementarity of chemical features of the compound with the positioning of amino acids in the active site of a target enzyme. Typically this involves iterations of synthesis, to modify the compound, and biophysical assay, to assess the outcomes. Selective targeting of the anti-cancer carbonic anhydrase isoform XII (CA XII), this process is challenging because the overall fold is very similar across the twelve CA isoforms. To enhance drug development for CA XII we used a reverse engineering approach where mutation of the key six amino acids in the active site of human CA XII into the CA II isoform was performed to provide a protein chimera (chCA XII) which is amenable to structure-based compound optimization. Through determination of structural detail and affinity measurement of the interaction with over 60 compounds we observed that the compounds that bound CA XII more strongly than CA II, switched their preference and bound more strongly to the engineered chimera, chCA XII, based on CA II, but containing the 6 key amino acids from CA XII, behaved as CA XII in its compound recognition profile. The structures of the compounds in the chimeric active site also resembled those determined for complexes with CA XII, hence validating this protein engineering approach in the development of new inhibitors

PLBD: protein–ligand binding database of thermodynamic and kinetic intrinsic parameters

We introduce a protein–ligand binding database (PLBD) that presents thermodynamic and kinetic data of reversible protein interactions with small molecule compounds. The manually curated binding data are linked to protein–ligand crystal structures, enabling structure–thermodynamics correlations to be determined. The database contains over 5500 binding datasets of 556 sulfonamide compound interactions with the 12 catalytically active human carbonic anhydrase isozymes defined by fluorescent thermal shift assay, isothermal titration calorimetry, inhibition of enzymatic activity and surface plasmon resonance. In the PLBD, the intrinsic thermodynamic parameters of interactions are provided, which account for the binding-linked protonation reactions. In addition to the protein–ligand binding affinities, the database provides calorimetrically measured binding enthalpies, providing additional mechanistic understanding. The PLBD can be applied to investigations of protein–ligand recognition and could be integrated into small molecule drug design

Video and computerised soccer match analysis technology

Vytauto Didžiojo universitetasŠvietimo akademij

An improved summing Compton gamma-ray spectrometer

A simple ad hoc analog computer using semiconductor logarithmic elements is used to examine the coincident pulse-pairs from a summing Compton spectrometer for compatibility with the Compton scattering equation for the particular scattering angle being used. With the aid of this circuit, the total absorption fraction of the spectrometer can be raised almost to 100% by identifying and rejecting electronically those coincidences in which some of the energy of the incident photon has escaped from either detector. At the same time, the polarization sensitivity of the Compton spectrometer is also improved since coincidences in which multiple scattering has taken place are rejected. The system can also be used to make the spectrometer telescopic, selecting electronically rather than by heavy collimators the incident direction of interest. The latter capability may be useful in situations where there is an omnidirectional flux. Though scintillation crystals have been used here to demonstrate the principle, the technique would be equally applicable (and perhaps most useful) in a light and compact Compton spectrometer using semiconductor detectors.Peer reviewed: YesNRC publication: Ye