Lecture 9. Enzymology 1 Flashcards
What are the 9 characteristics of an enzyme ?
- Preferred substrate
- pH
- Temperature
- Localisation
- Reaction catalysed
- Mechanism of the reaction
- Physiological role and control or regulation of activity
- Impact of upregulation
- Inhibition or absence
What is enzyme kinetics ?
The study of the rate of enzyme catalysed reactions
What are catalysts ?
Substance that speeds up a reaction but that in itself is not consumed during the reaction (may be changed transiantly)
Are all biological catalysts proteins ?
Most are, some may be RNA
What causes enzyme specificity ?
The precise interaction of the enzyme and substrate
What reaction is catalysed by hydrolase and give an example ?
- Hydrolysis
2. Lipase
What reaction is catalysed by isomerase and give an example ?
- Rearrangement of atoms
2. Phosphoglucoisomerase
What reaction is catalysed by ligase/polymerase and give an example ?
- Join two or more chemicals together
2. Acetyl-CoA synthetase
What reaction is catalysed by lyase and give an example ?
- Split compounds without water
2. Fructose 1, 6 - biphosphate aldose
What reaction is catalysed by oxidoreductase and give an example ?
- Transfer electrons and H+ from one molecule to another
2. Lactic acid dehydrogenase
What reaction is catalysed by transferase and give an example ?
- Move functional groups between molecules
2. Hexokinase
What does trypsin cleave ?
The carboxyl side of lysine or argine
What does thrombin cleave ?
The arginine glycine bonds in particular sequences only
What are cofactors ?
Small molecules that some enzymes require for activity
What are the two types of cofactors ?
- coenzymes
2. metals
What are prosthetic groups ?
Tightly bound coenzymes
What is a holoenzyme ?
An enzyme with its cofactor
What is an apoenzyme ?
An enzyme without a cofactor
What is gibbs free energy ?
A thermodynamic function that describes the potential energy available for work
What does the free energy change tell us ?
The spontaneity but not the rate of the reaction
What is an exergonic reaction ?
A reaction which occurs without the input of energy, or spontaneously only if the change in gibbs energy is negative
What is an endergonic reaction ?
A reaction will not occur spontaneously only if the change in gibbs energy is positive
What is delta G independent of ?
How the reaction occurs
What do highly exergonic reactions have ?
Large K’eq values
