University:
Boston University
Course:
CAS BI 525 | Biology of Neurodegenerative Diseases
Academic year:

2023
Views:

113

Pages:

6
Author:

Sincere Parks

Control by Allostery: Enzyme Regulation Glycogen Phosphorylase: Control by Allostery & Phosphorylation (more active) Glycogen(n) + Pi + Glycogen(n-1) Control by Allostery: Enzyme Regulation Glycogen Phosphorylase: Control by Allostery & Phosphorylation (more active) Glycogen(n) + Pi + Glycogen(n-1) Control by Allostery: Enzyme Regulation Rabbit Muscle Glycogen Phosphorylase (dimer) Covalent phosphoryl group (activating) Allosteric positive effector 45° Notice that these are both near the subunit-subunit interface and both add a phosphoryl group This is the R-state. Is there are T-state? Active site Control by Allostery: Enzyme Regulation Rabbit Muscle Glycogen Phosphorylase Glycogen phosphorylase PDBids 8GPB and 7GPB AMP Phospho-Ser Active site Control by Allostery: Enzyme Regulation Rabbit Muscle Glycogen Phosphorylase Glycogen phosphorylase PDBids 8GPB and 7GPB AMP Phospho-Ser Active site Enzyme Regulation Key Concepts for Control of Enzyme Activity •Allosteric effectors bind to multisubunit enzymes, such as aspartate transcarbamoylase, thereby inducing cooperative conformational changes that alter the enzyme’s catalytic activity. •Phosphorylation and dephosphorylation of an enzyme such as glycogen phosphorylase can control its activity by shifting the equilibrium between more active and less active conformations. You should be able to: • Compare and contrast the actions of an allosteric effector, a competitive enzyme inhibitor, and a noncompetitive inhibitor. • Explain the structural basis for cooperative substrate binding and allosteric control in ATCase. • Why are such allosteric enzymes composed of more than one catalytic subunit? • Describe how phosphorylation and dephosphorylation control the activity of glycogen phosphorylase. • List some advantages of phosphorylation/ dephosphorylation cascade systems over simple allosteric regulation.