Studies of keratins in tongue coating samples of hepatitis B patients by mass spectrometry

Abstract

Pooled tongue coating samples from 64 hepatitis B patients and 24 healthy adults were studied and a major band of differential proteins was found by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The differential proteins in this band were identified and proved to be keratins by liquid chromatography/tandem mass spectrometry (LC/MS/MS) and Western blot analysis. Furthermore, relative quantification of the identified keratins was performed via using stable isotopic labeling and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), showing the higher expression level of these keratins in tongue coating samples of hepatitis B patients than healthy adults. These results provided additional information to understand the medical diagnosis depending on the tongue coating.

Analysis of the differentially expressed low molecular weight peptides in human serum via an N‐terminal isotope labeling technique combining nano‐liquid chromatography/matrix‐assisted laser desorption/ionization mass spectrometry

“…The spiked serum samples regularly showed the singly charged ion pairs with a 6 Da mass difference in MALDI‐MS, which not only minimized operational errors in quantitation but also simplified interpretation of the mass spectra. The intrinsic pyrimidine ring of the labeling reagent increased the peak intensities of target peptides in MS resulting fromthe increased gas‐phase basicity of the derivatized N‐terminus . For each spiked sample, the peak intensity ratios between [ d 0 ]‐DMPITC‐labeled peptides and their corresponding [ d 6 ]‐DMPITC‐labeled internal standards represent the relative amounts of [ d 0 ]‐DMPITC‐labeled peptides.…”

Analysis of low molecular weight compounds by MALDI-FTICR-MS

“…Then, [d 0 ]/[d 6 ]-DMMSP were used as derivatization agent for the studies of different expression levels of keratins in tongue coating samples of Hepatitis B patients by MALDI-MS and western-blot analysis. The results showed the higher expression level of these keratins in tongue coating samples of hepatitis B patients than healthy adults [186]. These results provided additional information …”

A Stable Isotopic Pre‐digestion Labeling Method for Protein Quantitative Analysis Using Matrix‐assisted Laser Desorption/ionization Mass Spectrometry

“…The peptide WWCNDGR was chosen and the relative errors of quantitative analysis were calculated ( Figure 4A), which show excellent values under 5% at a certain concentration ratio from 0.1 to 10. 33 The quantitative result could also be obtained from any other labeled peptides. This indicates that the method is capable of providing accurate quantitative information about proteins that are identified by only a single peptide.…”