SX20 Stopped-Flow Spectrometer - Pro-K Global Analysis Software
PC Pro-K Global Analysis and Data Simulation Software
Pro-K is a unique stand-alone software package providing global analysis of time resolved spectral data accompanied by a comprehensive data simulation capability. It features singular value decomposition (a type of factor analysis) allowing spectral component prediction and data reduction. Global fitting to an arbitrary reaction schemes is available through the use of fast numerical integration techniques coupled to a symbolic reaction scheme editor. True intermediate spectra of all coloured species are calculated together with their associated concentration profiles. Multi-wavelength kinetic and PDA data are ideally suited for analysis with Pro-K.
The capability to acquire multi-wavelength absorbance data (time-resolved spectra) is a standard feature of the SX20 system. For the data shown (below right), the SX20 was set to automatically acquire a series of kinetic traces at 10nm intervals across the wavelength range 350-750nm. Less than 2mL of each reagent was required for this experiment (including priming the flow lines with sample). Alternatively, one can set the instrument to record kinetics at two or more discrete wavelengths as selected by the user.
PC Pro-K enables global fitting to multi-wavelength kinetic datasets; simultaneously fitting each kinetic trace to the reaction model. The kinetic parameters obtained must satisfy all the wavelength data at each time point therefore provides a more robust fit than single wavelength analysis and enables the study of more complex reactions.
PC Pro-K includes a wealth of tools for viewing data and rapidly assessing the quality of fitted data. The figures (right) show 3-D and 2-D representations of the same dataset following transfer to PC Pro-K.
PC ProK also enables Singular Value Decomposition (SVD) of the dataset. This single-mouse click operation provides a model-free assessment of the number of spectrally distinct reaction components present in the reaction and, by isolating those components that contribute only random noise to the data, enables the user to remove noise elements and improve data quality. In more detail, SVD produces a set of basis spectra, time-dependent amplitudes and singular values. For the data shown here, SVD analysis indicated the presence of 4 distinct species - suggesting a possible 3-step reaction mechanism.
For global analysis of data sets, PC ProK uses an innovative reaction scheme editor in combination with numerical integration techniques to enable fitting. Reaction models are entered in the form of simple steps e.g. A + B > C, C <> D, D > E and the use of numerical integration places almost no limit on the level of complexity of the reaction model.
For the data set shown above, global analysis to the 3-step (pseudo first order) reaction model A>B>C>D (entered as A>B, B>C, C>D) yielded calculated rate constants of 62.9s-1, 2.8s-1 and 0.13s-1. Close agreement between the fitted curves and all the kinetic data was found - examples of fitted kinetic curves are shown below.
Examples of fitted kinetic curves (overlaid in red on the data) following global analysis of the entire dataset to a 3-step reaction model. The curves show are at 350nm (top) and 690nm (below) and are shown here on both a linear (left) and a logarithmic (right) timescale.
In addition to the optimised rates and the fitted kinetic curves and spectra, PC Pro-K also generates concentration profiles and best-fit spectra for each reaction component providing clear evidence and support for the presence of short lived reaction intermediates.
Calculated best-fit component spectra (top left) and concentration profiles (bottom right - on a logarithmic timescale) following global analysis of the data set to a 3-exponential model.
Click here for an introduction to global analysis.
Other SX20 Accessories
- SQ.1 Sequential mixing
- PDA.1 Photodiode array
- SEM.1 Scanning Emission Monochromator
- AM.1 Scanning Monochromator (far-UV)
- UV.1 Deuterium light source
- RC5.1 5µl cell cartridge
- FP.1 Fluorescence polarisation/anisotropy
- DD.1 Dual detection accessory
- DF.1 Dual fluorescence detection accessory
- AN.1 Anaerobic system
- QFA.1 Quench-flow adaptor
- Pro-K Global analysis for PC
- Pro-K II 2 nd Order Global analysis for PC
Click here to request a full PDF brochure for the SX20 Stopped-Flow Spectrometer and accessories.
SX20 - the ultimate gold standard in stopped-flow
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