The enzyme phosphofructokinase catalyzes the conversion of fructose-6-phosphate and adenosine triphosphate (ATP) to fructose 1,6-bisphosphate and adenosine diphosphate (ADP). Adenosine monophosphate (AMP) activates the enzyme phosphofructokinase (PFK) by binding at a site distinct from the substrate-binding site. This is an example of:.

This is an example of allosteric regulation or modulation.

Explanation: Allostery is a process by which a ligand binds to a site on the enzyme that is different from the substrate binding site. This site is different from the active site and it is called allosteric site. Allostery can be positive or negative. If the binding of the ligand to the allosteric site of the enzyme activates the binding of the substrate to the active site of the enzyme, it is known as positive allostery but if the binding of a ligand to the allosteric site of the enzyme inhibits the binding of the substrate to the enzyme active site, it is known as negative allostery or allosteric inhibition. The binding of ADP to the allosteric site of phosphofructokinase (PKF) activates the enzyme, it is therefore a positive allostery.

the planets have a circular orbit around the sun.