Table 2.

Affinity of SpeAl and mutant forms for 65Zn2+

Protein	Kd, μM
SpeAl	2.3 ± 2
SpeAl–Glu33Ala	5.8 ± 3
SpeAl–Asp77Ala	60 ± 30
SpeAl–His106Ala	120 ± 50
SpeAl–His110Ala	80 ± 30
SpeAl–Asp77Ala, His106Ala	>150

Each value represents the mean ± SD of results from at least three distinct experiments.