Mass Spectrometry Technique Allows Monitoring of Individual Proteins

A novel technique allows researchers to follow changes that occur in proteins during periods of stress or during development of a disease.

Investigators at the Scripps Research Institute (Jupiter, FL, USA) exploited the properties of two chemical compounds, dimedone and iododimedone, to trace modification of proteins at the site of cysteine amino acid residues.

They reported in the January 5, 2011, online edition of the journal Angewandte Chemie that analysis by mass spectrometry allowed detection of the interaction between the reagents and cysteine residues that had been modified by the process of S-hydroxylation. S-hydroxylation, which occurs when situations of stress trigger the release of reactive oxidative molecules, converts cysteine into a sulfenic acid. It is this acid that reacts with dimedone and iododimedone.

The mass spectrometry method was so sensitive that in addition to quantifying modifications to different proteins, it was able to monitor changes that occurred at the level of individual cysteines within a single protein.

"Chronic disease states such as cancer can involve the modification of signaling proteins through S-hydroxylation, but other housekeeping proteins may also be targets," said senior author Dr. Kate Carroll, associate professor of chemistry at the Scripps Research Institute. "This new 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. 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 chemists alike."

"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,” said Dr. Carroll. "Now you will 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 process."

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