 Small molecule binding to this phylogenetically variable cavity has been proposed to stabilize 6mer* of the targeted PBGS and consequently inhibit activity.Such allosteric regulators are known as "morphlocks" because they lock PBGS in a specific morpheein form (6mer*).ALAD enzymatic activity is inhibited by lead, beginning at blood lead levels that were once considered to be safe (<10 μg/dL) and continuing to correlate negatively across the range from 5 to 95 μg/dL.