Moirai: Modeling Biochemistry
Three cholas (women) preparing to weave. The one on the left holds a heavily laden drop spindle,
and is thus analogous to Klotho. The other two are patiently waiting. This is not
unreasonable, since usually far more
labor
is required to spin and process a sufficient quantity
of raw wool in preparation for weaving, than in the actual weaving itself.
The weaving is Bolivian, of llama, from the
neighborhood of La Paz. My thanks to
Denise Beusen
for bringing this back from her recent
astronomical expedition to those parts.
The cellular
machine weaves
together literally thousands of parts, each with unique structural and functional
properties. Both understanding how the cell works and
engineering
cells with novel
properties requires the description and analysis of the components and
their interactions. The ultimate aim of Moirai is to build a computational model
of intracellular physiology which accurately simulates the effects of experimental
manipulation. Apart from their intrinsic interest as
databases and automated reasoning systems
,
we believe such
models
will stimulate new
scientific discoveries and engineering practices. To solve the entailed computational and
analytical problems, we have focused our
initial efforts
on
describing the structure and function of simple biochemical systems, beginning with
glycolysis
.
A sufficiently realistic large-scale model needs to include detailed information on both
the structure of the molecular parts and their functions in biochemical reactions.
We are developing
representations
for
molecules and reaction biochemistry for use in databases of biochemical function. Our
approach
is to capture the ``natural language'' of biochemistry in a
layered graph grammar
,
Klotho
,
which permits interconversion among a
family of equivalent representations for compounds
,
and then operate on these with
rules
which express chemical and mechanistic aspects of the biochemical reaction (Atropos). The dynamics will eventually be included in
Lachesis. An overview of the system is
sketched here
.
We are using these representations to develop algorithms for several important types of computations. These computations include logical and kinetic simulation of sequential biochemical changes to molecules (``trace the atoms through the pathway''); automated pattern recognition and classification for molecules and biochemical reactions; and fundamental inquiries into the biochemical and dynamic structure of metabolism. The applications of our work may range from understanding fundamental cellular processes, to the prediction of probable metabolic routes of drugs and xenobiotics, to the design of organisms for increased yield of desirable compounds in industrial processes.