Relationship between umami taste acuity with sweet or bitter taste acuity and food selection in Japanese women university students.

Background And Objectives: Although there are many studies on the umami receptor and its signaling pathway, literature on the effect of umami taste acuity on dietary choices in healthy subjects is limited. The current study aims to clarify the relationship between umami taste acuity with sweet or bitter taste acuity, food preference and intake.

Methods And Study Design: Forty-two healthy Japanese female university students were enrolled.

Rapid and efficient MALDI-TOF MS peak detection of 2-nitrobenzenesulfenyl-labeled peptides using the combination of HPLC and an automatic spotting apparatus.

In this paper, we report MALDI-TOF ms analysis of 2-nitrobenzenesulfenyl (NBS) labeled peptides with the powerful aid of an LC-automatic spotting system. using this approach we analyzed mammalian sera (rat and mouse) as biological samples to demonstrate performance. The labeling was carried out using a binary set of 2-nitrobenzenesulfenyl chloride (heavy and light), which modified tryptophan residues in sample proteins.

Selective detection of 2-nitrobenzenesulfenyl-labeled peptides by matrix-assisted laser desorption/ionization-time of flight mass spectrometry using a novel matrix.

The 2-nitrobenzenesulfenyl (NBS) method, which is useful for quantitative proteome analysis, is based on stable isotope labeling of tryptophan residues with NBS chloride ((12)C(6)-NBSCl or (13)C(6)-NBSCl). We found that 3-hydroxy-4-nitrobenzoic acid (3H4NBA) is a more suitable matrix than 2,5-dihydroxybenzoic acid (DHB) for detecting NBS-labeled peptides by MALDI-quadrupole IT (QIT)-TOF MS . Furthermore, NBS-labeled peptides were selectively ionized and detected in a mixture of NBS-labeled and unlabeled peptides.

Improved 2-nitrobenzenesulfenyl method: optimization of the protocol and improved enrichment for labeled peptides.

We have developed the NBS (2-nitrobenzenesulfenyl) method, a quantitative proteome analysis method utilizing stable isotope labeling followed by mass spectrometry. The potential of this method was reported previously, and the procedure has now been further optimized. Here, we describe a procedure utilizing urea or guanidine hydrochloride as a protein denaturant, in conjunction with an improved chromatographic enrichment method for the NBS-labeled peptides using a phenyl resin column.

An approach to quantitative proteome analysis by labeling tryptophan residues.

This report describes a method for quantification and sequence identification of individual proteins in complex mixtures. The method is based on labeling with the chemical reagent 2-nitrobenzenesulfenyl chloride (NBSCl) in conjunction with tandem mass spectrometry. In this method, selective introduction of the 2-nitrobenzenesulfenyl (NBS) moiety onto tryptophan residues is achieved, and a 6 Da mass differential is generated using (13)C(6)-labeled NBSCl (NBSCl-(13)C(6)) and (12)C(6)-labeled NBSCl (NBSCl-(12)C(6)).

An efficient chemical method for dephosphorylation of phosphopeptides.

Phosphate moieties found on serine, threonine or tyrosine residues in peptides, e.g., in proteolytic digests of proteins, were cleaved using hydrofluoric acid or hydrogen fluoride-pyridine without side reactions.