Luciferin synthesis and organophosphate detection by a luminescent enzymatic cascade
A luminescence reaction modeled on fireflies can detect contamination
with organophosphates with high sensitivity, ease, and low cost. At the
center of this technology is a new enzymatic method for the synthesis
of analogues of luciferin, the substance that makes fireflies glow. As
reported by a team of researchers in the journal Angewandte Chemie, it could also be used in the field.
© Wiley-VCH, re-use with credit to 'Angewandte Chemie' and a link to the original article.
The widespread use of toxic organophosphate pesticides (OPs) is a
very serious global environmental and health problem. Among the concerns
are acute, often fatal poisoning cases in agriculture—particularly in
developing nations—and also toxic pesticide residues that accumulate in
food chains and freshwater reservoirs where they may instigate cancer,
Alzheimer’s, and diabetes, for example. In the EU and USA, OPs are
strictly regulated.
Conventional detection by chromatography/mass spectrometry is
complex, expensive, and not suitable for use in poor countries or in
remote areas. Test kits are usually not sensitive and are unreliable. A
team from Thailand and Japan has now developed an inexpensive, simple
test that detects OPs directly in foods and biological samples with high
specificity and extreme sensitivity without sample preparation.
The researchers led by Pimchai Chaiyen started with a new enzymatic
cascade reaction for the synthesis of luciferin analogues from phenolic
compounds, which they called the HELP reaction. Luciferin is the
substrate of the enzyme luciferase and causes fireflies to glow.
Bioluminescence catalyzed by luciferase is an important method used in
biochemical research and the analysis of toxicants. HELP makes it
possible to produce luciferin analogues much more easily than before,
without special expertise or toxic chemicals. Luciferin analogues
produce luminescence in different wavelengths and allow for the parallel
detection of different target molecules. Among others, the team
produced two previously unknown luciferin analogues. One of these
produces brighter light of a longer wavelength than the original, which
penetrates cells and tissues more efficiently. This facilitates
real-time imaging and helps to reduce the need for animal experiments.
The new method for detecting organophosphates is also based on HELP.
“LUMOS” (Luminescence Measurement of Organophosphate and Derivatives)
includes three reaction steps. First, an enzyme from soil bacteria
breaks down the OPs and/or their metabolites into phenol derivatives. In
the second step, these are converted into a luciferin analogue via the
HELP reaction. In the third step, the luciferin derivative is used to
produce a bioluminescence signal with firefly luciferase. The wavelength
can be used to differentiate between different OPs. The team was able
to detect five particularly toxic OPs, such as parathion (E605), in
concentrations of parts per trillion (ppt) in urine, blood serum, and
fruit, and without sample preparation.
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About the Author
Pimchai Chaiyen is
Professor of the School of Biomolecular Science and Engineering (BSE),
Vidyasirimedhi Institute of Science and Technology (VISTEC), Thailand.
Her research interests are in the broad areas of enzyme catalysis,
enzyme engineering, biocatalysis, metabolic engineering, synthetic
biology, and technology development in the areas of green, bio- and
circular economy.
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