Interaction between oligomers of stefin B and amyloid-beta in vitro and in cells.

To contribute to the question of the putative role of cystatins in Alzheimer disease and in neuroprotection in general, we studied the interaction between human stefin B (cystatin B) and amyloid-beta-(1-40) peptide (Abeta). Using surface plasmon resonance and electrospray mass spectrometry we were able to show a direct interaction between the two proteins. As an interesting new fact, we show that stefin B binding to Abeta is oligomer specific.

Quantification in comprehensive two-dimensional liquid chromatography.

Although the use of comprehensive two-dimensional liquid chromatography (LCxLC) as a powerful separation technique is continuously increasing, its employment in quantification experiments is rather limited. The present research is focused on the quantification of a series of standards, as well as real-world sample compounds, by using dedicated laboratory-constructed LCxLC software, developed through a novel approach. Moreover, the difficulties encountered during software operation, in various elution conditions, are described and discussed.

Application of comprehensive two-dimensional liquid chromatography to elucidate the native carotenoid composition in red orange essential oil.

In the present work, the ability of a LC x LC-DAD/APCI-MS method developed at this laboratory to identify the native composition of carotenoid in an extremely complex matrix such as red orange essential oil was demonstrated. To carry out this task, two independent and orthogonal separation mechanisms were coupled through a 10-port switching valve that simultaneously collected the eluent from a microbore cyano column used as the first dimension in normal phase mode and injected it to a conventional reversed phase monolithic C(18) column in the second dimension separation. By using this novel analytical technique together with the use of DAD and APCI-MS detectors it was possible to identify in the sample, without the need of any pretreatment, 40 different carotenoids.

Comprehensive multidimensional liquid chromatography: theory and applications.

Comprehensive two-dimensional (2D) liquid chromatographic (LC x LC) techniques can be considered innovative methods only recently developed and adopted in many configurations. The revolutionary aspect of comprehensive two-dimensional techniques, with respect to classical multidimensional (MD) chromatography, is that the entire sample is subjected to the 2D advantage. The major benefit is that the separation capacities of each dimension are multiplied, offering a high peak capacity to resolve samples of great complexity.

Elucidation of carotenoid patterns in citrus products by means of comprehensive normal-phase x reversed-phase liquid chromatography.

A novel approach for carotenoid analysis has been developed. Orange essential oil and juice carotenoids were separated by means of comprehensive dual-gradient elution HPLC, using normal phase with a microbore silica column in the first dimension (first D), reversed phase with a monolithic C18 column in the second dimension (second D), and a 10-port switching valve as an interface. An on-line photodiode array detector was used in order to obtain absorption spectra.

Separation of triacylglycerols in a complex lipidic matrix by using comprehensive two-dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection.

The present investigation describes the employment of a comprehensive 2-D HPLC system, based on the combination of a silver ion and an RP column, for the characterization of the triacylglycerol (TAG) fraction of a very complex lipidic sample: donkey milk fat. The TAGs were grouped on the resulting bidimensional contour plot according to their double bond numbers (aligned along vertical bands) and according to their partition numbers (aligned along horizontal bands). Peak assignment was supported by using atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection.

Determination of beef tallow in lard through a multidimensional off-line non-aqueous reversed phase-argentation LC method coupled to mass spectrometry.

The presence of tallow in lard is not easy to determine, due to the similarity of the composition of these two animal fats, which differ mainly in the distribution of fatty acids (FA) in the three positions of the glycerol molecule. The determination of the composition of the triacylglycerol (TAG) fraction of lard, tallow, and their mixtures was investigated by HPLC in combination with atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The presence of tallow in lard was determined through the study of the sn-POP/sn-PPO ratio by multidimensional HPLC.

Determination of triacylglycerols in donkey milk by using high performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry.

The separation and determination of triacylglycerols (TAGs), which are the main components of naturally occurring fats and oils, in milk fat is a challenging task due to the very complex nature of this matrix. In the present study the TAG fraction of donkey milk lipids has been characterized by using high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS). HPLC in reversed phase mode has been used for TAG separation and silver ion (Ag+) HPLC has been used as a second dimension to clarify and confirm the identification.