enzymes Flashcards
what is the induced fit model?
● enzymes are not a rigid structure
● various parts of an enzyme molecule move in response to its environment
● some movements are small, some movements are large
explain induced fit model
● substrate and active site are not complementary
● active site changes and becomes complementary
● substrate binds to active site - enzyme substrate complex
● active site puts pressure onto bond and hydrolysis happens quicker
● this reduces activation energy
how does pH affect rate of reaction?
● increased pH alters charge of amino acid - pH changes charge of R group
● breaks ionic bonds between R groups
● tertiary structure changes
● shape of active site no longer complimentary to substrate
● no enzyme substrate complexes formed
how does substrate concentration affect rate of reaction?
● initially, amount of substrate is limiting rate of reaction
● enzymes with empty active sites
● after point of saturation, enzyme active sites are limiting factor and increasing conc does not affect rate of reaction
● increase number of enzymes to increase rate of reaction
how does temperature affect rate of reaction?
● as temp increases, more KE, more successful collisions
● more enzyme substrate complexes
● as KE increases, hydrogen and ionic bonds break between amino acids (disulphide bridges don’t break)
● tertiary structure changes
● active site no longer complementary
what are the types of inhibiters?
● competitive - temporary
● non-competitive - permanent
what do enzyme inhibitors do?
● enzyme inhibitors reduce rate of an enzyme catalysed reaction by interfering with enzyme in some way
● effect may be permanent or temporary
how do competitive inhibitors work?
● similar shape to substrate
● binds to active site
● prevents enzyme substrate complexes
● temporary
how do non-competitive inhibitors work?
● binds to allosteric site (different part of enzyme)
● changes tertiary structure of enzyme
● alters active site shape
● no longer complimentary to substrate
● substrate cannot bind - permanent
● increasing substrate has no effect on rate of reaction
