4 research outputs found
Involvement of inducible nitric oxide synthase in cardiac dysfunction with tumor necrosis factor-α
3‑Aminoquinoline/<i>p</i>‑Coumaric Acid as a MALDI Matrix for Glycopeptides, Carbohydrates, and Phosphopeptides
Glycosylation and phosphorylation
are important post-translational
modifications in biological processes and biomarker research. The
difficulty in analyzing these modifications is mainly their low abundance
and dissociation of labile regions such as sialic acids or phosphate
groups. One solution in matrix-assisted laser desorption/ionization
(MALDI) mass spectrometry is to improve matrices for glycopeptides,
carbohydrates, and phosphopeptides by increasing the sensitivity and
suppressing dissociation of the labile regions. Recently, a liquid
matrix 3-aminoquinoline (3-AQ)/α-cyano-4-hydroxycinnamic acid
(CHCA) (3-AQ/CHCA), introduced by Kolli et al. in 1996, has been reported
to increase sensitivity for carbohydrates or phosphopeptides, but
it has not been systematically evaluated for glycopeptides. In addition,
3-AQ/CHCA enhances the dissociation of labile regions. In contrast,
a liquid matrix 1,1,3,3-tetramethylguanidium (TMG, G) salt of <i>p</i>-coumaric acid (CA) (G<sub>3</sub>CA) was reported to suppress
dissociation of sulfate groups or sialic acids of carbohydrates. Here
we introduce a liquid matrix 3-AQ/CA for glycopeptides, carbohydrates,
and phosphopeptides. All of the analytes were detected as [M + H]<sup>+</sup> or [M – H]<sup>−</sup> with higher or comparable
sensitivity using 3-AQ/CA compared with 3-AQ/CHCA or 2,5-dihydroxybenzoic
acid (2,5-DHB). The sensitivity was increased 1- to 1000-fold using
3-AQ/CA. The dissociation of labile regions such as sialic acids or
phosphate groups and the fragmentation of neutral carbohydrates were
suppressed more using 3-AQ/CA than using 3-AQ/CHCA or 2,5-DHB. 3-AQ/CA
was thus determined to be an effective MALDI matrix for high sensitivity
and the suppression of dissociation of labile regions in glycosylation
and phosphorylation analyses