Electrospray Ionization Ion-trap Mass Spectrometry (ESI-MS)

Purpose
Structure elucidation of oligosaccharides, glycopeptides, glycoproteins, and proteins.

Amount of Sample Required for Analysis
If the sample is a singly purified glycoprotein, we need a minimum of 500 pmol of material to produce a clear result, more if the sample is a crude protein.

General Criteria for Sample Preparation
Your sample should be pure, soluble in water or 50% methanol, and free of non-volatile salts, buffers, and detergents. In electrospray ionization, a sample solution is sprayed from a fused silica capillary and charged by a high potential difference between the Taylor cone and counter electrode (see figure). The ions are introduced into a quadrupole ion trap mass spectrometer. ESI-MS often produces a series of multiply charged ions. The method can be performed on samples up to 100 kDa.

On-Line Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS)

Purpose
On-line separation by HPLC and determination of the molecular weight of peptides and glycopeptides; mapping of glycosylation sites.

Amount of Sample Required for Analysis
A minimum of 500 picomoles of peptides or glycopeptides is required.

General Criteria for Sample Preparation
Your sample should be a singly purified glycoprotein, and soluble in water or 50% methanol, and free of non-volatile salts, buffers, and detergents. The peptides or the glycopeptides are separated by using liquid chromatography and introduced into the ESI-MS which produces a series of multiply charged ions. The LC-MS data are analyzed using the TurboSEQUEST software and database, which will provide the glycoprotein mapping.