A scientist from the Florida campus of The
Scripps Research Institute has devised a new method of analyzing and
quantifying changes in proteins that result from a common chemical process. The
new findings could provide new insights into the effects of a highly
destructive form of stress on proteins in various disease models, particularly
The study, published in
the online Early View of Angewandte Chemie, was designated by the
journal as a “very important paper,” a distinction bestowed on less
than five percent of its publications.
technique allows us to home in on which proteins are modified to a significant
extent during periods of stress and how that changes during disease
progression,” said Kate Carroll, an associate professor in the Scripps
Research Department of Chemistry who conducted the study with Young Ho Seo, a research
fellow at The Univ. of Michigan. “It gives us the chance to look more
closely at targets for possible therapeutic intervention. From a practical
standpoint, the technique is simple and will be accessible to biologists and
The new technique
focuses on the process of cysteine S-hydroxylation, which plays a role in a
number of events related to physiology in both health and disease, including
the regulation of signaling proteins in various disease states.
The ability of the new
technique to focus on signaling pathways, particularly in diseases such as
cancer, is critical.
states such as cancer can involve the modification of signaling proteins
through S-hydroxylation, but other housekeeping proteins may also be
targets,” she said. “Key to distinguishing which of these proteins
may be involved in pathogenesis is the ability to measure the amount of
S-hydroxylation at specific sites within a protein. Now you’ll be able to tell.
This should help accelerate target identification in these disease-related
signaling pathways and allow us to focus on proteins that are important to the
During periods of
cellular stress, caused by factors such as exposure to UV radiation or many
disease states, the level of highly reactive oxygen-containing molecules can
increase, resulting in inappropriate modification of proteins and cell damage.
One oxidant, hydrogen
peroxide, functions as a messenger that can activate cell proliferation through
oxidation of cysteine residues in signaling proteins, producing sulfenic acid
(i.e., S-hydroxylation); cysteine is an amino acid is synthesized in the body.
Extending the gains of
an earlier study
In a 2009 study, Carroll found that sulfenic acid served as an early warning
biomarker of the reaction between hydrogen peroxide and cysteine. Carroll
tagged the miniscule reaction target with a fluorescent dye antibody. With it,
Carroll was able to read the levels of sulfenic acid levels in various cell
lines, including breast cancer cells.
The new technique takes
those findings several steps further by allowing scientists not only to
quantify the modifications to various proteins, but also to monitor these
changes at the level of individual cysteines within a single protein.
Carroll used a class of
reagents called isotope-coded dimedone and iododimedone, which traps and tags
sulfenic acids, allowing the cysteine sites and modified proteins to be easily
identified. These probes, which are highly selective for sulfenic acid, allow
the S-hydroxylation process to be monitored at the exact site of the
The tagged proteins can
be then be analyzed by mass spectrometry, a standard technology used to
determine the precise make-up of proteins and other molecules.
should be widely accessible to the scientific community because it’s so
simple,” Carroll said. “It should allow researchers to identify
proteins with altered S-hydroxylation profiles whose function may lend insight
into events in disease progression and have utility as potential markers for