Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Förster resonant energy transfer in orthogonally arranged chromophores

We investigate the ultrafast resonant energy transfer of a perylene bisimide dyad by pump-probe spectroscopy, chemical variation, and calculations. This dyad undergoes transfer with near-unit quantum efficiency, although the transition dipole moments of the donor and acceptor are in a perfectly orthogonal arrangement to each other in the equilibrium geometry. According to the point dipole approximation used in Fo?rster theory, no energy transfer should occur. Experimentally we do, however, find an ultrafast transfer time of 9.4 ps. With the transition density cube approach we show that in the orthogonal arrangement the Coulombic interactions do not contribute to the electronic coupling. Through the change of the spacer in both length and chemical character, we can clearly exclude any Dexter-type energy transfer. The temperature effects on the Fo?rster resonant energy transfer rate demonstrate that energy transfer is enabled through low-frequency ground-state vibrations, which break the orthogonal arrangement of the transition dipole moments. The dyads presented here therefore are a first example that shows with extreme clarity the decisive role vibrational motion plays in energy transfer processes.     

Nucleotide and aldehyde analysis by HPLC for determination of radical induced damage

Summary The analysis of two metabolite groups, nucleotides and aldehydes, is necessary for assessment of oxygen radical metabolism during hypoxia and reoxygenation.Nucleotides and their derivatives were determined by HPLC using gradient elution with 10 mM NH₄H₂PO₄ buffer containing 2 mM t-butylammoniumphosphate and acetonitrile.Aldehydes occuring after lipid peroxidation were analyzed by derivatisation to dinitrophenylhydrazones followed by TLC and HPLC separation with methanol/water on an ODS column.     

Über die Wirkungen von Aldehyden auf gesunde und maligne Zellen, 3. Mitt.: Synthese von homologen 4-Hydroxy-2-alkenalen,II

Zusammenfassung Eine einfache Synthese für 4-Hydroxy-2-alkenale wird beschrieben. Gesätt. Aldehyde werden bie tiefer Temp. mit Propargylaldehyd-diäthylacetal-magnesiumbromid zu den entsprechenden 4-Hydroxyalkynal-diäthylacetalen umgesetzt. Die Dreifachbindung wird mit LiAlH₄ zurtrans-Doppelbindung hydriert. Die 4-Hydroxy-2-alkenaldiäthylacetale werden mit verd. Citronensäure zu den 4-Hydroxy-2-alkenalen verseift.