My scientific work is in the field of mathematical modelling of biological processes, with the following major topics:

1. Structural analysis of biochemical networks.
2. Metabolic Control Analysis.
3. Further work
4. References

I am interested in structural properties of biochemical networks such as non-negative conservation relations,
the set of all non-negative steady-state fluxes and elementary modes of functioning. An elementary mode is
a minimal set of enzymes that can operate at steady state, with all the irreversible reactions operating in the
appropriate direction (Schuster and Hilgetag, 1994, see publication list below). Elementary modes can be
interpreted as biochemical pathways. Together with David Fell, Claus Hilgetag, John Woods, and Thomas Pfeiffer,
we have developed algorithms and computer programs for detecting these patterns in networks of any complexity,
for example, the program METATOOL, which can be downloaded from that site and an archive in Oxford.
The algorithm for computing all elementary modes in biochemical networks of any complexity can be downloaded
as a PDF file.

There is also a version that can be used online: phpMetatool. It was developed by Hagen Hoepfner and
Matthias Lange in Magdeburg.
Recently, I am trying to apply such topological methods to the reconstruction of bacterial metabolism, in cooperation
with Dr. Peer Bork's group, in particular with Thomas Dandekar (University of Wuerzburg and EMBL, Heidelberg).
Another application is in metabolic engineering, where it is of interest to find biochemical synthesis routes allowing a
maximal conversion yield.
Another method developed concerns the block-diagonalization of the null-space matrix. This allows one to decompose
biochemical networks into subsystems that are completely independent with respect to flux. This procedure is performed
by the program BlocDiag written in C by Ferdinand Moldenhauer and myself. It can be downloaded by ftp.

This analysis was developed in the early 70's by Drs. Heinrich & Rapoport in Berlin and Drs. Kacser & Burns in
Edinburgh (for a comprehensive bibliography established by Athel Cornish-Bowden (Marseille), click here).
My contributions concerned the analysis of flux control insusceptibility (with Ronny Schuster), comparison of the
existing definitions of control coefficients (with Reinhart Heinrich), and further elaboration on a modular approach
to control analysis (with Daniel Kahn and Hans Westerhoff). Furthermore, I worked out a proof of an invariance
property of co-response coefficients and appropriate definitions of control coefficients in nonideal systems and on
control analysis of metabolic systems involving quasi-equilibrium reactions (with Johann Rohwer, Hans Westerhoff,
B.N. Kholodenko and Marta Cascante). I elaborated on a method for phrasing the fundamental equations of MCA
in terms of generalized variables.

Further work concerns the study of optimal properties of enzymatic systems (maximization of catalytic efficiency, stability)
and the interrelation of transmembrane potential and pH difference across membranes with electrogenic proton pumps.
I have also been involved in the development of models for calcium oscillations and their interrelations with ER membrane
potential oscillations (in collaboration with Milan Brumen and Marko Marhl from Maribor, Slovenia).