Composable Rate-Independent Computation in Continuous Chemical Reaction Networks

Area of Science:

• Synthetic biology
• Molecular computing
• Chemical kinetics

Background:

• Biological systems process information via chemical interactions.
• Engineering molecular computing systems using chemical reaction networks (CRNs) is a key challenge.
• CRNs model chemical interactions for computational analysis.

Purpose of the Study:

• To investigate function computation using rate-independent and composable CRNs.
• To identify design principles for constructing such CRNs.
• To characterize the computational capabilities of these systems.

Main Methods:

• Focus on CRNs where initial concentrations are inputs and equilibrium concentrations are outputs.
• Analyze rate-independent CRNs (computation independent of reaction rates).
• Analyze composable CRNs (computations can be concatenated).

Main Results:

• A necessary and sufficient condition for composable, rate-independent CRNs is that output species are not reactants within their module.
• Functions computable by such CRNs are characterized as superadditive, positive-continuous, and piecewise rational linear.
• Composability significantly restricts rate-independent computation capabilities.

Conclusions:

• Specific structural constraints are required for composable, rate-independent CRNs.
• The class of computable functions is mathematically characterized.
• Advanced input/output encoding strategies are needed to expand computational power.