Bio-activation of simeprevir in liver microsomes and characterization of its glutathione conjugates by liquid chromatography coupled to ultrahigh-resolution quadrupole time-of-flight mass spectrometry.

Liquid chromatography coupled to a triple quadrupole and, alternatively, to an ultrahigh-resolution quadrupole time-of-flight (UHR-QqTOF) mass spectrometers was used to collect qualitative and quantitative information from incubations of the anti-hepatitis C drug simeprevir with human and rat liver microsomes, respectively, supplemented with NADPH and glutathione. For this, different chromatographic methods using two different chromatographic columns, Kinetex® 2.6 µm C (50 × 3 mm) and Atlantis T3 (100 Å, 3 µm, 4.

The Radical SAM enzyme NirJ catalyzes the removal of two propionate side chains during heme d biosynthesis.

Heme d is a modified tetrapyrrole playing an important role in denitrification by acting as the catalytically essential cofactor in the cytochrome cd nitrite reductase of many denitrifying bacteria. In the course of heme d biosynthesis, the two propionate side chains on pyrrole rings A and B of the intermediate 12,18-didecarboxysiroheme are removed from the tetrapyrrole macrocycle. In the final heme d molecule, the propionate groups are replaced by two keto functions.

Artifacts in amine analysis from anodic oxidation of organic solvents upon electrospray ionization for mass spectrometry.

Different phenylenediamines were used to explore anodic oxidation in solution during electrospray ionization (ESI) mass spectrometry analysis. In our experiments, a series of unknown ionic species was detected in the phenylenediamine solutions. Our results propose that reactions of phenylenediamines with species formed by anodic oxidation of typical ESI solvents during the electrospray ionization process such as formaldehyde are producing these peaks.

Studies on the interaction of the antibiotic moenomycin A with the enzyme penicillin-binding protein 1b.

The interaction of a moenomycin derivative with the enzyme penicillin binding protein 1b (PBP 1b) has been studied by means of STD NMR. The results obtained initiated the synthesis of a number of moenomycin derivatives modified in unit A including a moenomycin-ampicillin conjugate and determination of their antibiotic activities. A protocol is described that allows studying the interaction of moenomycin analogues with PBP 1b by fluorescence correlation spectroscopy.