  Recon 2 is a highly curated reconstruction of the human metabolic network.
Whilst the network is state of the art, it has shortcomings, including the
presence of unbalanced reactions involving generic metabolites. By replacing
these generic molecules with each of their specific instances, we can ensure
full elemental balancing, in turn allowing constraint-based analyses to be
performed. The resultant model, called Recon 2.1, is an order of magnitude
larger than the original.
