Enzymes Flashcards
What are enzymes?
Catalysts
What do catalysts do?
Increase the rate of a reaction repeatedly and decrease activation energy of a reaction, and are not consumed by the reaction
What do enzymes not do?
Change the ratio of the concentrations of products to reactants at equilibrium and alter the amount of energy consumed or liberated in the reaction
What special environment is provided by an enzyme’s active site?
catalysis occurs when substrate is held at the active site
What functional groups can be involved in catalysis?
almost all alpha amino and carboxyl groups are tied up in peptide bonds R groups
Some enzymes employ _________ or _________ groups at their active sites
coenzymes; prrosthetic
Coenzymes
metals or small organic molecules not covalently bound to protein
prosthetic groups
small organic molecules typically covalently linked to protein
How do enzymes catalyze biochemical reactions?
involves basic principles of organic chemistry
Do enzymes physically interact with their substrates to affect catalysis?
Yes
E
Enzyme
S
Substrate
ES
Enzym/substrate complex
ES*
Enzyme/transition state complex
P
Product
EP
Enzyme/Product complex
What do substrates bind to?
Enzyme’s active site
How do substrates bind?
by Hydrogen bonding, hydrophobic interactions and ionic interactions
Lock and key model
substrate (key) fits into a perfectly shaped space in the enzyme (lock)
Induced fit model
substrate fits into a space in the enzyme, causing the enzyme to change conformation
Following catalysis, what happens to the products?
binds less tightly or no longer fits in the active site and is released
To assay an enzyme, you could measure what?
the 1. appearance of colored product made from an uncolored substrate
the 2. disappearance of a UV-absorbent substrate that is converted into a non-UV-absorbent substrate
3. the appearance of radioactive product made from a radioactive substrate
Continuous assays units
[P] vs time
End Point Assay units
[P] vs time
