Global and target analysis of time-resolved spectra

In (bio)physical/(bio)chemical research time-resolved spectroscopy is used to disentangle complex kinetics. To extract maximal information from the overwhelming amount of data that is generally obtained, a model based analysis is mandatory. A model characterized by assumptions regarding the measurement process and physico-chemical knowledge is formulated in our approach using
building blocks representing different aspects of the system at a variety of levels. Often employed building blocks include an instrument response function and a compartmental description of the kinetics. By parameterizing the system in greater detail (including more, or more complicated, building blocks), the fit between data and model is often improved. For example, by arameterization
of both the kinetic and the spectral aspects of the system, a spectro-temporal model is obtained whose application allows more precise parameter estimation compared to a purely kinetic model. Parameter estimates obtained by fitting models for time-resolved spectra to experimental data provide a concise description of the system that yields insight into the underlying dynamics.

Contact: Ivo van Stokkum, e-mail:
Department of Physics and Astronomy

Flow chart of modeling the initial photocycle of Photoactive Yellow Protein (PYP). Traces
at 4 wavelengths are shown at the top right. The kinetic model scheme comprises of five
states (indicated by the color of the box), of which the Species Associated Spectra (SAS)
and rate constants have been estimated