Allosteric Regulation and Feedback Inhibition

define allosteric regulation

when an enzyme’s functionality at the active site is affected by the binding of a regulatory molecule (activator or inhibitor) at an allosteric site

either inhibits or stimulates an enzyme’s activity

allosteric inhibitors function like _____________ inhibitors

non-competitive

how many polypeptide chains are allosterically-regulated enzymes made of?

2-4

does each subunit have its own active site?

yes

2 major conformations of allosterically-regulated enzymes

active and inactive

do allosterically-regulated enzymes oscillate between both forms?

yes

define activators

bind to the allosteric site of the enzyme and stabilize it in its active form

define inhibitor

binds to the allosteric site and stabilizes it in the inactive form

define cooperativity

when one substrate binds and it allows for others to bind more easily

define feedback inhibition

when a metabolic pathway is switched “off” by the binding of an end product to the allosteric site of an enzyme earlier in the pathway

in a metabolic pathway, the product of one = the _________ of the next

substrate

why is feedback inhibition important?

it prevents the cell from wasting resources by synthesizing more product than necessary