NEWS OF TH E WEEK
SOLVING BIOFUELS’ REDOX EQUATION The overlap between the natural fluorescence of cyanobacteria (red) and that of the probes (green) demonstrates that the probes enter living microbes.
probes covalently label reactive cysteine amino acids on proteins inside living cyanobacteria, but only when the cysteine thiol group is in its reduced form. “We want to identify proteins where redox chemistry acts like a switch, and where keeping that switch on keeps production of your hydrogen or alkane fuel flowing,” said Aaron T. Wright, who led the research. Natalie C. Sadler, who presented the work in the Division of Biological Chemistry, and her colleagues used confocal microscopy to demonstrate that the probes enter Synechococcus cyanobacteria. They starved the microbes of nutrients or, because the microbes use photosynthesis, switched between light and dark. Both are extreme instances of what might happen inside a bioreactor. The team tracked changes over time in reduced and oxidized cysteines. Their list of redox-sensitive proteins includes several enzymes already known to be redox-regulated, but others on the list, including gene transcription regulators, were not (Front. Microbiol. 2014, DOI: 10.3389/fmicb.2014.00325; ACS Chem. Biol. 2014, DOI: 10.1021/cb400769v). Kate Carroll, a protein redox regulation expert at Scripps Florida, said the research unearths “an exciting array of protein targets” for making better cyanobacteria-based biofuel factories. Not all the enzymes the team found are necessarily major metabolic switches, Wright said. “So now we’re dying to dig in and see which ones truly are.”—CARMEN
ACS MEETING NEWS: Probes
could reveal ways to boost microbial fuel output
OR SOMETHING SO TINY and brainless, cyano-
F
ACS CHEM. BIOL.
bacteria have proven awfully hard to push around. The blue-green microbes are promising hosts for biofuel production. Yet attempts to boost output by engineering the microbes’ genomes rarely work in big bioreactors. Researchers at Pacific Northwest National Laboratory think setbacks happen because the biochemistry that regulates fuel compound production isn’t fully understood. At the American Chemical Society national meeting in San Francisco, they presented molecular probes that might help close that knowledge gap. The probes reveal metabolic pinch points regulated by oxidation and reduction of cysteine side O chains on enzymes. Such reactions are H commonplace and help cells reO N N O spond to their environment, H O including the stresses of being Iodoacetamide redox probe coaxed to make biofuels. The
DRAHL
MAKING CASHEWS LESS ALLERGENIC ACS MEETING NEWS: Sulfite treatment
reduces binding of antibody to allergenic proteins from cashews
REE NUTS SUCH AS CASHEWS can be dan-
T
gerous to the many people who are allergic to them. Improved processing methods might help reduce the allergenicity of cashews, according to research presented in the Division of Agricultural & Food Chemistry at the American Chemical Society national meeting in San Francisco. The main allergens in cashews are proteins called Ana o 1, Ana o 2, and Ana o 3. Previous work has shown that some of these allergenic proteins are sensitive to strong reducing agents. Now, Christopher P. Mattison and coworkers show that when two of these allergenic proteins are treated with the mild reducing agent sodium sulfite, the antibodies that trigger the allergic reaction are less likely to recognize them. Sodium sulfite is approved for use in food processing and is “generally recognized as safe” by the Food & Drug AdminCEN.ACS.ORG
6
SHU TTERSTOCK
I
istration. The researchers treated aqueous extracts of ground raw and roasted cashews with 50 mM sodium sulfite at temperatures ranging from 0 to 100 °C (J. Agric. Food Chem. 2014, DOI: 10.1021/jf501117p). The researchers tested the treated extracts on serum samples from people who are allergic to cashews. They observed a reduction in antibody binding to Ana o 2 and Ana o 3 in treated extracts. They saw the largest effect with the extract that had been heated to the highest temperature. Being able to use an approved agent such as sodium sulfite to reduce allergenicity “has significant appeal,” said Kenneth H. Roux, a biology professor at Florida State University who studies food allergens. However, he noted, the sulfite concentration used to treat the aqueous extract was relatively high; still higher concentrations would probably be needed “to treat more complex foods” such as whole nuts, he suggested. “Even if successful, sulfite treatment could significantly alter or negatively affect food quality.” Mattison and coworkers already have under way further studies with whole cashews. “We will also need to assess safety, nutritional, and sensory aspects of the treated nuts,” he said. “The goal is to process nuts so that they are unable to cause allergic reactions, but if we can reduce or eliminate the number of lifethreatening severe reactions, that would be a great step forward.”—CELIA ARNAUD
AUGUST 18, 2014
