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,
© 2006 Bio-Rad Laboratories, Inc.
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.
© 2006 Bio-Rad Laboratories, Inc.
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