Search

Matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is increasingly used to analyze native and oxidized lipids. However, as the majority of MALDI devices are operating under high vacuum, the detection of volatile compounds such as “small” aldehydes is difficult and requires previous derivatization. This study uses 2,4-dinitrophenylhydrazine (DNPH) to efficiently convert aldehydes into hydrazones that can be easily identified by the characteristic mass shift and their selective enrichment by precipitation. Additionally, the UV absorption of the hydrazones at 337 nm is sufficiently high allowing direct analysis without typical MALDI matrices. Finally, it will be shown that the presence of DNPH does also enable the detection of non-oxidized phospholipids. [ABSTRACT FROM PUBLISHER]

The interest in the analysis of lipids and phospholipids is continuously increasing due to the importance of these molecules in biochemistry (e.g. in the context of biomembranes and lipid second messengers) as well as in industry. Unfortunately, commonly used methods of lipid analysis are often time-consuming and tedious because they include previous separation and/or derivatization steps. With the development of “soft-ionization techniques” like electrospray ionization (ESI) or matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF), mass spectrometry became also applicable to lipid analysis. The aim of this review is to summarize so far available experiences in MALDI-TOF mass spectrometric analysis of lipids. It will be shown that MALDI-TOF MS can be applied to all known lipid classes and the characteristics of individual lipids will be discussed. Additionally, some selected applications in medicine and biology, e.g. mixture analysis, cell and tissue analysis and the determination of enzyme activities will be described. Advantages and disadvantages of MALDI-TOF MS in comparison to other established lipid analysis methods will be also discussed. [Copyright &y& Elsevier]

Acylation of antimalarial and bacteriostatic sulfonamides with N-protected amino acids and peptides was carried out using standard peptide coupling methods. These acylation reactions are regioselective for the N4 nitrogen atom of diazine-containing sulfonamides. In contrast, only N1 coupling was found for sulfisoxazole, an isoxazole-based sulfonamide. Computational studies suggest that a combination of geometrical, thermodynamic and electronic factors are responsible for the different reactivities reported. [Copyright &y& Elsevier]