250 one millisecond emission
scans from an
OLIS RSM 1000F and a single
stopped-flow shot
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Each scan has high noise.
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Each scan was collected in one millisecond.
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Each one millisecond data point contains time,
wavelength, and intensity information.
The Answer:
correct kinetics, plus spectra,
minus noise
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The 250 one msec scans globally fitted to an A -> B
chemical model (colored species A changes into
colored species B, i.e, one form of the protein changes
into another form).
The protein underwent an amplitude drop and a
wavelength shift during its chemical denaturation.
The fit took an instant.
The single wavelength alternative
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A kinetic trace acquired at one wavelength and fit
to the exponential “colored A -> colorless A in the
presence of a colored background B”
Not only is there no information about the
intensity shift,
no information about the wavelength shift,
but a good fit to the wrong chemical model looks
acceptable
Minimum sample and maximum results
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While an OLIS RSM 1000 is capable of negligible
noise levels under good conditions, life often does
not offer us good conditions.
This example illustrates what is possible when
working with a single stopped-flow shot's data.
Either the correct spectral and
kinetic answer with
greatly reduced noise
Or, the kinetic answer
with noise remaining
And the potential (even likelihood in
many cases) for incorrect conclusions
about the chemistry
Graduate to the OLIS RSM 1000
and OLIS GlobalWorks software
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Only with the DeSa rapid-scanning monochromator is millisecond spectral
scanning possible (as opposed to multiple wavelength acquisition from a diode
array)
This monochormator is employed in our absorbance, fluorescence, and CD
spectrometers
This example used high noise emission scans to illustrate the power and value of
global data analysis.
“Global analysis” starts with SVD, followed by Downhill Simplex, followd by
Matrix Exponentiation ... all taking literally the blink of an eye on a megabyte
data set.
Global fitting of hundreds of high (or low!) noise scans return the correct
answers in an instant.