Figure 2.

pH-dependence of the overall rate constant k_q for the rhenium-tyrosine complex in H₂O and D₂O. The experimental data for k_q measured with 10mM phosphate buffer in H₂O (Figure 3 in Ref. [14]) are depicted with open circles (○). The rate constants for the phosphate-acceptor model with 10mM phosphate buffer calculated using Eq. (14) are depicted with thick and thin lines for the reaction in H₂O and D₂O, respectively. The rate constant for the reaction in H₂O or D₂O is plotted as a function of pH or pD, respectively, where the mole fraction $\chi ({\text{HPO}}_4^{2-})$ or $\chi ({\text{DPO}}_4^{2-})$ is calculated as a function of pH or pD using Eq. (15) with pKa = 7.2 or 7.8, respectively. Figure reproduced with permission from Ref. [37].