Gas chromatographic-mass spectrometric method for trazodone and a deuterated analogue in plasma

A plasma assay method for trazodone and a 2H4 analogue is described which uses gas chromatography--electron-impact selected-ion monitoring mass spectrometry. Etoperidone is used as an internal standard. The analytes are extracted from basic medium into n-butyl chloride, then back extracted into aqueous 0.1 M hydrochloric acid. The aqueous layer is made basic and re-extracted with n-butyl chloride. The solvent is reduced under nitrogen at 35 degrees C and the residue is redissolved in toluene for gas chromatographic--mass spectrometric analysis. The ions monitored are m/z 231, 235, and 225 for trazodone, [2H4] trazodone and etoperidone, respectively. Quantitation is in the range 40-1000 ng/ml with acceptable precision and accuracy. The method is suitable for biopharmaceutical studies.     

Affinity capillary electrophoresis applied to the studies of interactions of a member of heat shock protein family with an immunosuppressant

The bioaffinity of receptor-ligand interactions is investigated by determining the binding constant (association constant or dissociation constant) of the resulting complex utilizing affinity capillary electrophoresis (ACE). The ACE binding assay was established with a potent immunosuppressant, deoxyspergualin (DSG), that binds specifically to Hsc70, a constitutive or cognate member of heat shock protein 70 (Hsp70) family. Quantitative determination of binding constants under different running buffer systems provide comparative results. The association constants for the interaction between Hsc70 protein and DSG were found to be 5.7·10⁴ M⁻¹ in a buffer with pH 6.95 and 6.3·10⁴ M⁻¹ in a buffer with pH 5.30 (or corresponding dissociation constants, 18 and 16 μM, respectively) based on Scatchard analyses. Binding of DSG to a synthetic peptide, SINPDEAVAYGAAV-QAAILSGDK, one of the DSG-binding fragments found from tryptic digest of Hsc70 protein, provides further detailed information for the understanding of Hsc70 binding domain. The applicability of using coated capillaries was also evaluated for probing Hsc70-DSG interaction.     

Functional Hydride Transfer by a Thiolate‐Containing Model of Mono‐Iron Hydrogenase featuring an Anthracene Scaffold

We report the synthesis, X‐ray structure and functional biomimetic activity of a model complex of mono‐iron hydrogenase (Hmd). To achieve the desired biomimetic fac‐CNS(thiolate) ligation motif, an anthracene framework is used to provide the requisite donors in a single chelate. A bulky aryl thiolate (ortho dimethylphenyl) is included to achieve mononuclearity. In addition to exhibiting structural (X‐ray) and spectroscopic (NMR, IR) similarity to the enzyme, the complex is competent for H₂ activation (heterolysis) and hydride transfer to a model substrate—mimicking the functional behavior of the enzyme in a biomimetic CNS coordination sphere for the first time.