Understand competitive and noncompetitive inhibition

A substrate that acts as a "positive motivator" of, or to enhance a metabolic pathway, is also known as a positive feedback regulator or a substance that has a positive feedback mechanism.

Statement I is false because increasing the substrate concentration will only help overcome competitive inhibition. Noncompetitive inhibition can only be overcome if the inhibitor is removed from the enzyme.

Statement II is also false because competitive inhibitors do not change the active site. They bind to the active site and prevent substrates from binding. Noncompetitive inhibitors bind elsewhere on the enzyme and alter the shape of the active site, thereby preventing substrate binding.

Statement III is true because noncompetitive inhibition does not affect the enzyme affinity for substrates. The enzyme still has the same affinity, but the substrates can’t bind because of the altered active site.

Noncompetitive inhibition is a type of enzymatic alteration that results in changes to enzymatic function without alterations to the active site. If the active site was to be blocked, this compound would function via competitive inhibition. The other terms do not describe any type of enzymatic inhibition process in the human body. Be able to distinguish the difference between competitive and noncompetitive inhibition.

Competitive inhibition occurs when an substrate or inhibitor compete with the normal substrate for binding the active sight of an enzyme. The proper functioning of the enzyme depends on the concentration ratio of inhibitor to enzyme or substrate to enzyme. The competitive inhibition of the enzyme in this case by the antibiotic has potentially bactericidal or bacteriostatic effect on the bacteria until that antibiotic concentration decreases. Negative feedback involves the product of a set of metabolic reactions inhibiting the formation of a precursor of that metabolic pathway, thereby decreasing its own production.

Negative feedback interrupts a metabolic pathways by producing a substrate that inhibits enzymes in the beginning steps of the metabolic cycle. If a chemical is "mimicking" substrate C or causing Substrate C to be produced before other steps in a cycle, the enzyme is inhibited by the excess of substrate C thus the pathway can not continue. Most such molecules are proteins that interact with enzymes.