3.6.1.17 beta-mercaptoethanol slight activation 3.6.1.17 dithiothreitol slight activation 3.6.1.17 EDTA able to reverse Zn2+ inhibition 3.6.1.17 fructose 2,6-diphosphate able to reverse Zn2+ inhibition, ineffective on the enzyme without Zn2+ 3.6.1.17 phosphate activating below 30 mM