Fast characterization of industrial soy protein isolates by direct analysis with matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Industrial soy protein isolates (SPIs) due to differences in their processing conditions may differ both in composition and in degree of hydrolysis. As a result, they display different performance in food production and final food properties like consistency and taste. To address this issue, a fast, cheap, and simple method for screening and characterization is required.

Principles of laser-induced separation and transport of living cells.

Separation and transport of defined populations of living cells grown on a thin membrane can be achieved by laser microdissection (LMD) of the sample of interest, followed by a laser-induced forward transport process [laser pressure "catapulting" (LPC)] of the dissected cell cluster. We investigate the dynamics of LMD and LPC with focused and defocused UV-A laser pulses by means of time-resolved photography. Catapulting is driven by plasma formation when tightly focused pulses are used, and by confined thermal ablation at the bottom of the sample for defocused catapulting.

Mechanisms of laser-induced dissection and transport of histologic specimens.

Rapid contact- and contamination-free procurement of histologic material for proteomic and genomic analysis can be achieved by laser microdissection of the sample of interest followed by laser-induced transport (laser pressure catapulting). The dynamics of laser microdissection and laser pressure catapulting of histologic samples of 80 mum diameter was investigated by means of time-resolved photography. The working mechanism of microdissection was found to be plasma-mediated ablation initiated by linear absorption.

Principles of laser microdissection and catapulting of histologic specimens and live cells.

Rapid contact- and contamination-free procurement of specific samples of histologic material for proteomic and genomic analysis as well as separation and transport of living cells can be achieved by laser microdissection (LMD) of the sample of interest followed by a laser-induced forward transport process [laser pressure "catapulting," (LPC)] of the dissected material. We investigated the dynamics of LMD and LPC with focused and defocused laser pulses by means of time-resolved photography. The working mechanism of microdissection was found to be plasma-mediated ablation.

Localization of noncovalent complexes in MALDI-preparations by CLSM.

The unambiguous detection of noncovalent complexes (NCCs) by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is still a far cry from being routine. For protein NCCs such as their quaternary structure it has been reported that signals of the intact complex are only obtained for the first or at most the first few laser exposures of a given sample area. This observation was called the first-shot phenomenon.

MALDI-TOF-MS analysis of bacterial spores: wet heat-treatment as a new releasing technique for biomarkers and the influence of different experimental parameters and microbiological handling.

Short wet heat-treatment is presented as a new technique to release high-mass biomarkers to obtain strain-specific fingerprints of intact bacterial spores by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). Wet heat-treatment was applied for several minutes (3-30) by two techniques using either a screw-cap tube submerged in a glycerol bath at 120 degrees C or an Eppendorff-tube submerged in a water bath at 100 degrees C. Both techniques turned out to be successful for releasing high-mass biomarkers.

Localization of analyte molecules in MALDI preparations by confocal laser scanning microscopy.

In this study, the incorporation of Texas Red-labeled avidin into crystals of 2,5-dihydroxybenzoic acid (2,5-DHB) and 2,6-DHB (used as matrixes for matrix-assisted laser desorption/ionization (MALDI)) was investigated by fluorescence spectrophotometry and confocal laser scanning microscopy (CLSM). The analyte distribution in crystals, grown slowly under controlled conditions, was compared to the analyte localization in different standard preparations (dried-droplet and thin-layer preparation). Texas Red turned out to be a useful fluorescence label in the acidic environments of typical matrixes.