Enzymes Flashcards
(18 cards)
What are apoenzymes
They are enzymes with out a prosthetic group
What are haloenzymes
They are enzymes with a prosthetic group
What are the two general ways to increase the speed of chemical reactions
- Add heat
- Add a catalyst
True of false: Biological catalysts have different structure than other proteins
False, biological catalysts have the same structures as proteins
It is also stabilized by the same non-covalent interactions
- hydrophobic interactions
- hydrogen bonds
- ion pairs
- van der waals
- disulfide bridges depending on the environment
Are enzymes specific?
Yes enzymes are highly specific
Why do non-biological enzymes have a greater capacity for regulation
Because conformational change in protein structure is possible
How do enzymes work
Enzymes speed up reaction rates
What is considered to be a high energy bond
It has to release a minimum of -25 kj/mol
How much energy does breaking a phophoanhydride bond create
-30 kJ/mol
Which chemical reactions are thermodynamically favorable (exergonic or endergonic)
Exergonic because they have a negative change in G
(They are spontaneous)
What is the highest free energy state in a reaction, what does it do?
The transition state
It determines the activation barrier for the reaction
Thermodynamics
What determines the speed of a biochemical reactions
The size of the activation energy barrier
Enzymes can also speed up reactions
(Kinetics)
What are 4 ways that catalysts lower the activation energy barrier
- Remove substrates from aqueous solutions (desolvation)
- Proximity and orientation effects
- Taking part in the reaction mechanism
- Stabilizing the transition state
What are the 2 different sites that an active site can be made of
- catalytic site
- substrate binding site
What is the correct model for enzyme and substrate binding, describe it
Induced fit model
Shape of active site resembles TS
It removes substrates from aqueous solution (basically isolates the substrate) and squeezes out H20
What are the advantages of an enzyme isolating the substrate
- Prevents water interference
- Forms H bonds is more effective in a non (Aq) env
- It eliminates energy barrier that the solvent makes
What do co-factors do to enzymes
Help with their function
What amino acids can be involved in nucleophilic (covalent) catalysis?
Asp, Glu, Ser, Tyr, Cys, Lys, His
