Question

Biochemistry: The opening sentence in this wikipedia article turns on its head my understanding of the definition of Allosteric regulation - http://en.wikipedia.org/wiki/Allosteric_regulation

"In biochemistry, allosteric regulation (or allosteric control) is the regulation of a protein by binding an effector molecule at a site other than the protein's active site."

What about O2 binding to heme in hemoglobin. This is a binding at the active site that induces positive allosteric modulation at the remaining heme groups.

Is this not a contradiction to the wikipedia article?

Answer 1

Hemoglobin is not an enzyme - but a transport protein - no reaction occurs at heme groups, thus they are not active sites.