Module 2: Biological Molecules pt 2 Flashcards
two word phrase for an enzyme
biological catalyst
4 step process of enzyme Action
1)enzyme + substrate entering active site
2)enzyme/substrate complex
3)Enzyme/product complex (weakly bound)
4)enzyme + product leaving active site
Lock + Key hypothesis
-Active site specific to one substrate like a lock is specific to a key
-substrate binds to active site of enzyme forming enzyme/substrate complex
-R groups in active site react with substrate, putting strain on it
-The strain helps to create or break bonds, separating or joining substrates
-active site remains unchanged
-activation energy reduced
how is Induced fit hypothesis differences to Lock + Key
-Weak initial interaction between enzyme + substrate
-Enzyme tertiary structure changes slightly to bind to substrate
-more strain on substrate, lowering activation energy
What are competitive inhibitors
Inhibitor molecule has similar shape to substrate and block enzymes active site
example of competitive inhibitors
Statins, asprin, antibiotics (penicillin)
for competitive inhibitors what does degree of inhibition depend on
the relative concentration of substrate, inhibitor, enzyme
what are Non competitive inhibitors?
Inhibitor molecule which binds to the enzyme away from the active site (the allosteric site).
It changes the tertiary structure of the actives site so it cannot bind to the substrate
examples of Non competitive inhibitors
cyanide, arsenic, organophosphates
does Increasing substrate concentration effect the degree of inhibition of Non competitive inhibitors
no
How do prosthetic groups help enzymes?
tightly bound- form permanent part of enzyme (active site)
give an example of a prosthetic group of an enzyme and it’s role
Example = Zn^2+
Important part of structure of carbonic anhydrase
Enzyme in the metabolism of CO2
Why is Precursor Activation needed?
- To activate the enzyme in certain conditions
- To prevent the enzyme damaging tissues
What is an inactive precursor
an enzyme found in an inactive form
how does Precursor Activation happen with a inorgancic molecule
what is the enzyme called before and after this
. Addition of cofactor to an inactive precourser
Before this, enzyme = apoenzyme
After, enzyme = holoenzyme
how does Precursor Activation happen without an inorganic molecule
give an example of this
. Change in conditions
Example = pepsinogen
Released into stomach
Acidic pH causes conversion to pepsin
what is a Cofactors
non-protein ‘helper’ inorganic molecule or ion
how are cofactors obtained
Obtained via diet
how do cofactors work
Bind loosely to the enzyme so that a substrate can bind to active site
give an example of a cofactor and its role
Example = Cl-
Needed for amylase to form the correctly shaped active site
what is a Coenzyme
an organic ‘helper’ molecule
waht are coenzymes derived from
Mostly derived from vitamins
example of coenzyme and its role
Example – Vitamin B3 needed to synthesise NAD
NAD = coenzyme used in respiration
are coenzymes changed in the reaction?
yes
+they can also be changed to be used between two enzymes - recycled+