アブストラクト
| Date | 14:00-15:00 Sep 25, 2024 |
| Speaker | Atsushi Mochizuki Kyoto University Japan |
| Title | Biological functions and functional modules originated in structure of chemical reaction networks |
| Abstract |
Biological functions are emerging from dynamics of chemical reaction
networks, and regulated by changes in amount/activities of enzymes
mediating reactions in the system. In this talk, I present our recent
theoretical approaches to determine behaviors of chemical reaction
systems induced by changes in enzyme amount/activities from network
topology alone. We found that (1) qualitative responses of chemical
concentrations (and reaction fluxes) by enzymatic changes are determined
from a network structure alone. (2) The nonzero responses are localized
in finite extents in a network, and each of the extent is determined by
a subnetwork called a "buffering structure". A buffering structure is
defined from local topology of the network by an equation -(#" of
chemicals" )+(#" of reactions" )-(#" of cycles" )+(#" of conserved
quantity" )=0, where the index is an analogous to the Euler
characteristic. We proved that any perturbation on a reaction parameter
in a buffering structure does not influence concentrations and fluxes
outside the buffering structure. Finally, (3) buffering structures
govern the bifurcation of steady stats of reaction networks. The
bifurcation behaviors are localized inside buffering structures, and the
bifurcation condition of each substructure is determined from network
topology. We apply our method to some real networks, including
cell-cycle or carbon metabolism systems, and demonstrate how we can
understand behaviors of biological systems from network structures alone.
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