Revealing Formylation Sites in Intact Amphibian Disulfide Peptides: A Top-Down Study Using ExD.

Mass spectrometry contributed significantly to the creation of proteomics as a science and is now the principal analytical tool of proteomics. Although the bottom-up approach remains the most popular, more and more studies apply the top-down method for sequencing. Novel tandem mass spectrometry methods resolved numerous sequencing problems and allowed for the analysis of intact peptides and even proteins.

Tomato LeAGP-1 is a plasma membrane-bound, glycosylphosphatidylinositol-anchored arabinogalactan-protein.

Arabinogalactan-proteins (AGPs) are a class of highly glycosylated, hydroxyproline-rich glycoproteins that function in plant growth and development. Tomato LeAGP-1 represents a major AGP expressed in cultured cells and plants. Based on cDNA and amino acid sequence analyses along with carbohydrate and other biochemical analyses, tomato LeAGP-1 is hypothesized to be a classical AGP localized to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor.

Alpha,2-, alpha,3-, and alpha,4-dehydrophenol radical anions: formation, reactivity, and energetics leading to the heats of formation of alpha,2-, alpha,3-, and alpha,4-oxocyclohexadienylidene.

We have regiospecifically generated the alpha,2-, alpha,3-, and alpha,4-dehydrophenoxide anions by collisional activation of o-, m-, and p-nitrobenzoate. The alpha,2 and alpha,4 isomers also were synthesized by reacting o-benzyne radical anion with carbon dioxide and electron ionization of p-diazophenol. All three dehydrophenol radical anions were differentiated from each other and identified by probing their chemical reactivity with several reagents.