Figure 1.

System parameters for convenience kinetics. The homoserine kinase reaction (HK, dotted box) transforms homoserine and ATP into O-phospho-homoserine and ADP (solid arrows). Threonine inhibits the enzyme (dotted arrow). Each node and each arrow carries one of the system parameters: each metabolite is characterised by an energy constant k^G, the reaction by a velocity constant k^V, and each arrow by a k^M or k^I value. The system parameters are thermodynamically independent and can assume arbitrary positive values. The turnover rates for forward and backward direction can be computed from the system parameters.