Enzymes are globular proteins that act as biological catalysts and speed up the rate of
metabolic reactions by lowering the activation energy, remaining unchanged by that
reaction
intracellular enzymes:
Catalase in liver cells
● Breakdown of Hydrogen peroxide into oxygen and water by hydrolysis
extracellular enzymes:
Amylase made in pancreatic cells but secreted to the digestive system
● Breakdown of starch to maltose in small intestine
Trypsin made in pancreas but operates in the small intestine
● Hydrolysis of peptide bonds in proteins into smaller peptides
Enzyme action
Reaction:
- Molecules must collide with enough activation energy in the correct orientation
Enzymes increase the likelihood of successful collisions and reduce activation energy
1
, Specificity: enzymes can only bind to 1 substrate b/C they are complementary to the shape
of the substrate
Lock and key
Shape of active site is fixed
= only 1 substrate is complementary
- Form ES complex = reaction
- ED complex = products then leave the active site
Induced fit model
Shape of active site goes through a conformational change (changes slightly) to fit the
shape of the substrate more closely/perfectly
Temperature
Increases:
1. Molecules gain kinetic energy and vibrate more
2. Increased collision frequency btw substrate and active site
3. More ES complexes formed = more product made in a given time
Rate of reaction increases up to optimum where :
- Molecules gain too much kinetic energy and vibrate too much
- Strained hydrogen and ionic bonds in the tertiary structure of the enzyme break
- Active site changes shape and the enzyme denatures so is no longer complementary
to the shape of the substrate
- Substrate cannot bind to the active site
- No enzyme-substrate complexes form = no product made
- Rate of reaction rapidly decreases
2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller erikakumar. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.91. You're not tied to anything after your purchase.
