Many proteins are enzymes Flashcards
How do enzymes act as biological catalysts?
they provide an alternative route for the reaction with a lower activation energy which speeds up the rate of reaction
What is the induced-fit model of enzyme action?
- substrate binds to active site (not completely complementary)
- causes active site to change shape to become complementary
- forms enzyme-substrate complex
- causes bonds in substrate to distort lowering activation energy
How have models of enzyme action changed over time?
- initially lock & key model suggested that active site is completely complementary to one substrate
What is the specificity of enzymes?
- specific tertiary structure determine shape of active site which depends on sequence of amino acids
- active site is complementary to specific substrate which induced shape of active site forming enzyme-substrate complex
What is the effect of enzyme concentration on the rate of enzyme-controlled reactions?
- as enzyme conc increases rate of reaction increases so more enzyme-substrate complexes form
- after a certain point rate of reaction levels off as substrate becomes limiting factor (all substrate in use)
What is the effect of substrate concentration on the rate of enzyme-controlled reactions?
-as substrate conc increases the rate of reaction increases forming more E-S complexes
- after a certain point rate of reaction levels off as enzyme becomes limiting factor (all enzymes in use)
What is the effect of temperature on the rate of enzyme-controlled reactions?
- as temp increases to optimum rate of reaction increases as there is more kinetic energy so more E-S complexes form
- as temp increases above optimum rate of reaction decreases because enzyme denatures - H/ionic bonds break changing the shape of the active site so fewer E-S complexes form
What is the effect of pH on the rate of enzyme-controlled reactions?
- as pH increases/ decreases past optimum rate of reaction decreases
- enzyme denatures - H/ionic bonds break changing the shape of the active site so fewer E-S complexes form
How does the conc of competitive inhibitors effect the rate of enzyme-controlled reactions?
- as conc of competitive inhibitors increases the rate of reaction decreases
- they have a similar shape to substrate so bind to active site, blocking substrate from binding
- fewer E-S complexes form
- increasing substrate conc can reduce effect of inhibitors
How does the conc of non-competitive inhibitors effect the rate of enzyme-controlled reactions?
- as conc of non-competitive inhibitors increases the rate of reaction decreases
- they bind to allosteric site changing the shape of active site
- active site is no longer complementary to substrate so fewer E-S complexes form
- increasing substrate conc doesn’t effect rate of reaction as change to active site is permanent