Figure 1.

Absorption spectra of wild type and mutant rcSHMT in the absence and presence of substrates. Left panels show the absorption spectra of wild type, T254A and T254C rcSHMTs at 30°C before (black lines) and after the addition of 90% saturating glycine (blue lines). Green lines are spectra taken after the addition of 100 μM H₄PteGlu to the samples containing glycine. Right panels show the absorption spectra of the same enzymes before (black lines) and after the addition of 90% saturating L-serine (red lines).