Structural elements of the arylglycerol β-syringyl ether type are very frequent in hardwood lignins. A variety of crystalline dimeric lignin models representing different diastereomeric forms of structural elements in lignin of this type have been studied using X-ray crystallography. Bond distances and bond angles in the model compounds are in all probability nearly identical with those of the ...

The environmental carcinogen benzo(a(pyrene-7,8-diol-9,10-epoxide (BPDE) forms DNA adducts with unique stereochemistries that may have divergent biological fates, depending on how they are processed within a cell. To investigate the effect of DNA bulky adduct stereoisomerism on the mutagenic outcome of translesion DNA replication in a human cell ex tract, oligonucleotides were synthesized that ...

Penicillins may be regarded as acylation products of 6-aminopenicillanic acid (Figure 1). This bicyclic dipeptide results from cyclization of L-Cysteinyl-L-valine (1) and is loosed into the culture medium in good yield when a strain of Penicillium chrysogenurn (W.51.20) is cultured in the absence of side chain precursors suitable for acylation at the 6-amino grouping (2). With the attainment of...

The use of 4-chlorotestosterone acetate by farmers for cattle fattening was recently demonstrated although the use of this anabolic steroid is strictly forbidden in the European Union. We investigated the metabolism of 4-chlorotestosterone acetate in the bovine species after intramuscular and oral administration. Nineteen metabolites were detected in urine after intramuscular injection, and eig...

For a rigorous analysis of the receptor-ligand binding, speciation of the ligands caused by ionization, tautomerism, covalent hydration, and dynamic stereoisomerism needs to be considered. Each species may bind in several orientations or conformations (modes), especially for flexible ligands and receptors. A thermodynamic description of the multispecies (MS), multimode (MM) binding events shows...