... [42].Tyrosines have been found to interact with flavins in amyriad of arrangements, including, for example, spa-tial T-shaped arrangements [12,34], planar parallel anddisplaced stacks [1,2,13,43,44] ... binding rather than beingdirectly involved in the hydride transfer reaction [21].Our results, together with the amino acid arrangementobserved in the catalytic site, indicate that C266 mayconstrain ... astructural rearrangement on NADP+binding. Takentogether, it is suggested that this conformationalchange in protein structure may allow enzyme negativeco-operativity to occur between substrates,...