RTP Reports on Phosphate-Modulated Mg Binding to AP
The binding of phosphate to AP is known to modulate the binding
of metals to the active site. We were able to observe the effect
this has on the environment of W109 as evidenced by measuring the RTP lifetime.
The RTP decay was measured at several phosphate concentrations with only
Mg bound to the protein. The observed effect of phosphate means that
Mg must be binding into at least one of the two Zn binding sites when no
Zn is present. This is consistent with observations of Cd and Tb
binding to all three metal-binding sites.
Figure 7: Lifetime distributions by MEM analysis of apo AP incubated
with 0.5 mM MgCl2 show a modulation of the
two peaks as the phosphate concentration is increased.
H/D Exchange Increases the apo AP RTP Lifetime