Flashcards
Conformational Changes in Proteins
Flashcards do conjunto (13)
- 1What does binding of an ion or metabolite involve?- non-covalent interactions
- stereoselectivity
- conformational changes - 2What is key to cellular activity?- molecular recognition
- successful binding - 3What is the function of induced fit? Give an example.- substrate strain
- supports catalysis
- allows conformational adjustment
- forms favourable micro-environment
- excludes unfavourable molecules
- glucose --> glucose-6-phosphate - 4What is the role of allosteric regulation? Give an example.- often multimeric
- binding at one site alters the binding of the substrate to the active site
- primes enzyme to be active/inactive
- e.g. inhibition of PFK by ATP and citrate - 5What are the two methods for determining protein structure?- NMR
- X-ray diffraction - 6Describe the use of NMR.- in solution, aqueous phase
- good for globular proteins
- assesses conformational flexibility
- detects interactions between magnetic isotopes with an applied magnetic field - 7Describe the use of X-ray diffraction.- solid state
- for fibrous and globular proteins
- generates structures at atomic resolution for molecules that form regular crystals
- comparing active and inactive states
- X-rays scattered by electrons in crystals = e density map = distribution of atoms - 8What is the relationship between theta and [L] for a protein with a single binding site? Define theta and [L] and give an example.- theta = fraction of sites occupied by L
- L = ligand
- if Kd is high, theta is low = less stability
- relationship predicts a hyperbolic curve
- interaction of P and L is independent of [L]
- e.g. myoglobin - 9What is the relationship between theta and [L] for a multimeric protein? Give an example.- relationship fails
- sigmoidal curve
- cooperativity in the binding curve
- e.g. oxygen binding to haemoglobin
- oxygen affinity increases as pO2 increases
- due to allosteric effects
- concerted model - 10Describe the concerted model of cooperativity.- each subunit has 2 conformations
- tense = inactive, low affinity for substrate, strong interaction with other subunits
- relaxed = opposite
- all subunits have to be in the same conformational state - 11What cellular activities are conformational changes key to?- signalling
- enzyme pathways
- synthesis - 12How are conformational changes important in signalling? Give an example.- mechanism for sensing the state of a cell + surroundings
- hormone binding to receptors e.g. adrenaline binding to beta-adrenergic receptor
- different subunits have different functions - 13Describe the functions of the different subunits in signalling. Give an example.- regulatory = receive signal and transmit to the catalytic subunits by conformational changes
- activation of cAMP-dependent protein kinase
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- Prelims Cells FlashCards sobre Conformational Changes in Proteins , criado por Kirstin Latimer em 06-01-2016.
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- Kirstin Latimer
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