LEC 12: Regulation of enzyme activity Flashcards
What does the regulation of enzyme activity do?
Regulates complex metabolic pathways
Enzyme activity is regulated in 5 principle ways
- Allosteric control
- Covalent modification (on/off switch)
- Proteolytic cleavage
- Isoenzymes
- Genetic control
What are the characteristics of allosteric control (4)
- Regulation of enzyme activity by binding of small molecules at regulatory sites
- Reversible binding
- Regulated by products of the pathway under their control
- Binding results in conformational changes in the enzyme (changes enzyme activity)
What are the characteristics of Covalent modification (2)
- Addtional or removal of a FG on an Aa of the enzyme (activate or deactivate enzyme)
- Reversible covalent attachement
What are the 2 types of covalent modification and what form they synthesize
- Covalent activation: Enzyme synthesized in inactive form (activated)
- Covalent inhibition: Enzyme synthesized in active form (deactivated)
Reversible ___ is the most widespread covalent modification
Phosphorylation
Define what Proteolytic cleavage does
Breakdown of proteins into smaller polypeptides or Aa
Many enzymes are synthesized in a catalytically inactive precursor form, called a ___, to mask an activity that would otherwise be detrimental to the parent cell
Zymogen
What happens in Acute pancreatitis
Enzymes become activated before leaving the pancreas which lead to auto-digestion
What are the characteristics of Isozymes (3)
- Homologous enzymes, within a single organism, that catalyze the same reactions, but differ in structure
- Different Aa sequences, different kinetics, and different regulatory properties
- Encoded by different genes
What are the characteristics of Genetic control (2)
- Take place at the level of gene transcription
2. A molecule induces the expression of an enzyme
Define Transcription factors
Molecules that control the expression of a certain gene
