Amide Surrogates with Restricted Rotation of a rBond

Amide surrogates such as aminimides, phosphonamides, and sulfonamides Fig. 13.4 display high conformational flexibilities and have been used to mimic the tetrahedral transition state of proteases. The intriguing aminimides display interesting biological properties 22 and have been introduced in peptidomimetic inhibitors of elastase 23 and HIV-1 protease 24 and are found in the diuretic agent besulpamide. In these compounds, the high resonance O C-N- -O-C N fixes the amide bond in trans x 180...

Cyclophilins and FKBPs Similar Molecular Basis for Distinct Catalytic Mechanisms

The PPIase domains of cyclophilin and FKBPs do not display any similarities whereas members within each subfamily show a high degree of homology in sequence and in three-dimensional structure, suggesting that conservation of the overall shape of the active site and of certain residues is essential for PPIase activity. Moreover, both enzymes feature structural differences from parvulins, in particular Pinl Fig. 12.2 1,9,12 . Fig. 12.2 Ribbon three-dimensional structures of hCyp18 and hFKBP12 and...

B trans [CoIIICl2NH34

Fig. 14.1 The ComCl2 NH3 4 ion complex A is green and B is violet. To consider Werner's model for coordination compounds totally consistent, it is imperative to show not only the existence of the other isomer for complexes of the CoCl2 NH3 4 type but also for others containing different ligands like Co NO2 2 en 2 , and Co NH3 2 en 2 3 or Co NH3 4 py 2 3 , where the species in the inner coordination sphere of the metal are neutral. Thus, for this purpose by about 1913 approximately two dozen...

Identification of Cis Trans Isomers

The identification of isomers is as important as their synthesis and purification. The technique to be used for this purpose depends on the species to be analyzed and if it is in solution or in solid state. Without doubt if there are crystals of the material to be analyzed the best way to do it is by X-ray diffraction, but there are other techniques that can be used, such as infrared and Raman spectroscopy, electronic paramagnetic spectroscopy, nuclear magnetic resonance, and electronic...