Bio-Rad ProteinChip Matrices User Manual

ProteinChip®Energy Absorbing Molecules (EAM)

Instruction Manual

Catalog #C30-00001, #C30-00002, #C30-00003, #C30-00004

For technical support, call your local Bio-Rad office, or in the US, call 1-800-4BIORAD

(1-800-424-6723).

Introduction

ProteinChip energy absorbing molecules (EAM) are an essential component of successful ProteinChip SELDI system experiments. EAM is a generic name for molecules that assist in desorption and ionization of the analyte. Known as “matrix” in traditional MALDI mass spectrometry, EAM are applied in organic solvent, solubilizing many proteins on the array surface. As the EAM dry, the proteins cocrystallize with the EAM. These crystals absorb the laser energy and generate the ionized proteins detected by the ProteinChip SELDI system.

Product Description

Bio-Rad offers three EAM for the detection of proteins and peptides. The general guidelines for choosing EAM are based on the molecular weight (MW) and chemical nature of the analyte, but there are no absolute rules.

ProteinChip CHCA EAM, 5 mg/vial

ProteinChip alpha-cyano-4-hydroxy cinnamic acid (CHCA) EAM (MW 189.2) are especially good for small molecules, 1–30 kD.

ProteinChip SPA EAM, 5 mg/vial

ProteinChip sinapinic acid (SPA) EAM (MW 224.2) are recommended for all larger proteins, but also work reasonably well for peptides. In general,

ProteinChip SPA EAM give better resolution and fewer multiply charged ions than ProteinChip EAM-1 EAM. For protein profiling using only one kind of EAM, ProteinChip SPA EAM are the molecules of choice.

ProteinChip EAM-1 EAM, 5 mg/vial

ProteinChip EAM-1 EAM are proprietary molecules (MW 231.21) and work well for proteins in the 10–50 kD mass range. ProteinChip EAM-1 EAM prove useful in allowing desorption and ionization of proteins that are difficult to detect, such as glycosylated proteins. It should be noted that ProteinChip EAM-1 EAM tend to generate multiply charged species, and peaks tend to be broader due to more adduct formation.

Preparing ProteinChip EAM in Solution

ProteinChip EAM in solution can be prepared in a number of different ways that may optimize the detection of the proteins in your sample. Table 1 to the right lists the steps for preparing EAM in solution using commonly used solvent systems. For a comprehensive list of solvent solution options, please see the ProteinChip SELDI System Applications Guide, Volume 1.

+ 5 hidden pages