Enzymes & Enzyme Kinetics Flashcards
What are enzymes?
Protein catalysis that
- increase the velocity of the reaction and
- not consumed during the reaction
What kind of shape do enzymes have?
Three-dimensional that fit the shape of reactant (substrate)
What is the name RNA with catalytic activity?
And what does it catalyse?
Ribozyme
Cleavage and synthesis of phosphodiester bond
Common property of enzymes as biological catalyst?
Increase the velocity of spontaneously occurring reaction WITHOUT altering the chemical equilibrium
What do enzymes do to the activation energy (Ea) and the rate of reaction (RoR)?
Lower the Ea so RoR increases
How do enzymes differ from other catalysts?
- Highly specific
- interact with 1 or few substrate
- catalyse only one type of reaction - Highly efficient
- increase RoR x100-1000 - Act under mild physiological conditions
- pATM, pH7, 37ºC - Activity and synthesis strongly regulated in cells
What is holoenzyme?
An active enzyme with its non-protein component
What is apoenzyme?
An inactive enzyme without its non-protein component
What is the non-protein moiety made of?
Cofactor - metal ion Zn2+/Fe2+ (bind tightly)
Coenzyme - small organic molecule (bind loosely)
In what ways do coenzymes associate with enzymes?
Cosubstrates - transiently associate; disassociate from enzyme in altered state
Prosthetic group - permanently associate; return to original form
Give 3 examples of Coenzymes and where they are derived from
*NAD - from nicotinic acid (B3)
Coenzyme A - from pantothenic acid (B5)
**FAD - from riboflavin (B2)
- (nicotinamide adenine dinucleotide)
- *(flavin adenine dinucleotide)
What are prosthetic groups?
Tightly bound cofactors (covenant bond)
Can be metal ion or organic molecule
What are cofactors?
Type of enzyme partner group that aids in enzyme functionality (Zn2+/Fe2+)
What are coenzymes?
A specific type of cofactor that are ‘organic’, works in active site, NAD, FAD
What is the relationship between holoenzymes, apoenzymes, non-protein component?
Holoenzyme = apoenzyme + non-protein component
K = [apoenzyme][non-protein component]
——————————————————-
[holoenzyme]
If K -> 0 then strong interaction (prosthetic group)
If K > 0 then weak interaction (coenzyme)
