Competitive INHIBITION Competitive inhibitors compete with substrate for an enzyme's active site, lowering the enzyme's likelihood of binding substrate and slowing the observed reaction velocity.

The inhibitor-distorted active site has trouble converting the substrate to product before it dissociates, resulting in a lowered apparent substrate binding affinity.

Mixed inhibitors do not bind directly in the active site, and therefore do not block substrate binding, but instead bind at sites that can be proximal or distal from the active site.