Enzyme activators are molecules that bind to enzymes and increase their activity.
An example of an enzyme activator working in this way is fructose 2,6-bisphosphate, which activates phosphofructokinase 1 and increases the rate of glycolysis in response to the hormone glucagon.
Hexokinase-I (HK-I) is an enzyme activator because it draws glucose into the glycolysis pathway. Its function is to phosphorylate glucose releasing glucose-6-phosphate (G6P) as the product. HK-I not only signals the activation of glucose into glycolysis but also maintains a low glucose concentration to facilitate glucose diffusion into the cell.
PFK: R-state Biological tetramer complex with fructose-6-phosphate, ADP and Mg+2 ion; generated from 4pfk by QPS