Assessment of Nodal Rigidity and its Response to Metabolic Engineering - Since information on the degree of nodal rigidity is needed for chosing an appropriate technology for metabolic engineering, various methods have been used for assessment of rigidity of a branch point or a node.

This information can be obtained using mathematical models of metabolism, metabolic control theory (MCT) or biochemical system theory (BST). In these approaches, simulations of a network arc conducted to assess rigidity. Various technologies of metabolic engineering, when applied to a network may also yield information about nodal rigidity.

Further, the node 1 is flexible and, node 2 is strongly rigid, and B1 does not inhibit its own synthesis. In this case, if B₁ branch is blocked, the yield of P would increase due to flexibility of node 1, but if B₂ branch is blocked, the yield of P will actually decrease, since due to rigidity of lode 2, flux will be diverted to BI and the flux towards P will be attenuated.

If instead, node 1 is rigid and node 2 is, flexible, then blocking B₂ will improve yield of p, but if BI is blocked, although yield of P will not be affected, the rate of the synthesis of P will be severely attenuated, due to the effect of flux distribution at S.