Approaching an experimental electron density model of the biologically active trans ‐epoxysuccinyl amide group—Substituent effects vs. crystal packing

The trans-epoxysuccinyl amide group as a biologically active moiety in cysteine protease inhibitors such as loxistatin acid E64c has been used as a benchmark system for theoretical studies of environmental effects on the electron density of small active ingredients in relation to their biological activity. Here, the synthesis and the electronic properties of the smallest possible active site model compound are reported to close the gap between the unknown experimental electron density of trans-epoxysuccinyl amides and the well-known function of related drugs. Intramolecular substituent effects are separated from intermolecular crystal packing effects on the electron density, which allows us…

Electrostatic complementarity in pseudoreceptor modeling based on drug molecule crystal structures: the case of loxistatin acid (E64c)

After a long history of use as a prototype cysteine protease inhibitor, the crystal structure of loxistatin acid (E64c) is finally determined experimentally using intense synchrotron radiation, providing insight into how the inherent electronic nature of this protease inhibitor molecule determines its biochemical activity. Based on the striking similarity of its intermolecular interactions with those observed in a biological environment, the electrostatic potential of crystalline E64c is used to map the characteristics of a pseudo-enzyme pocket.

The Significance of Ionic Bonding in Sulfur Dioxide: Bond Orders from X-ray Diffraction Data

A novel refinement technique for X‐ray diffraction data has been employed to derive S-O bond orders in sulfur dioxide experimentally. The results show that ionic S-O bonding dominates over hypervalency.

Die Bedeutung ionischer Bindungsanteile in Schwefeldioxid - Bindungsordnungen aus Röntgenbeugungsdaten

CCDC 1498221: Experimental Crystal Structure Determination

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CCDC 977799: Experimental Crystal Structure Determination

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CCDC 1498220: Experimental Crystal Structure Determination

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