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In an alpha heliex R group ...
_______ makes a kink in the polypeptide chain
Higher Free Energy
- Less stable
- More concentrated
- More ordered
- Greater work capacity
Lower Free Energy
- More stable
- Less concentrated
- Less ordered
- Less work capacity
Objects tend to move from ....
Higher free energy to lower free energy
Free energy describes a _______ _______
Some biological states have higher free energy characterized by .....
Biological events are driven by movement from higher free energy to lower free energy
A catalyst changes the ....
Activation energy of a Reaction
Characteristics of Enzyme Action
- Enzymes are substrate-specific
- Region that binds substrate is active site
- Binding involves interactions between enzyme's R-group and substrate
- Binding destabilizes bond(s) in substrate
What happends to the enzymes shape
it changes temporarily
Interactions with R-groups at active site ....
stabilize tansition state
What do enzymes do?
- Active site binds substrate (reactants) -> substrate specifcity
- Binding involves interactions between enzyme's R-groups and substrate
- Binding destabilizes chemical bonds in substrate -> lowers the activation energy -> reaction goes faster
Enzymes do not ....
Enzymes do .....
- add energy to the reaction
- Decrease the energy of activation for exergonic reactions
induced fit between enzyme and its substrate
Reactant Molecules Bind to ....
Specific Locations in and Enzyme
Interactions in the active site ...
(e.g. H bonding, charge interactions) stabilize the transition state
Factors that affect proteins ...
affect enzymes and thus affect the rate of a reaction
reaction rate =
amount of product formed (or substrate used) / time
Factors Affecting the Rate of a Reaction
- Substrate concentration
- Enzyme concentration
- pH (and the concentration of other ions)
Environmental factors that affect the rate of reaction
- Enzymes from different organisms may function best at different temperatures
- Enzymes from different organisms may function best at different pHs
Catalyze same reaction but have slightly different structures and/or localizations
- Enzymes may have different or NO affinity for different substrates
- Different substrates look different
- May or may not fit active site
- Enzyme might or might not 'like' different substrates
Enzyme Km Depends on ....
Affinity for Substrate
Substrate with highest affinity for enzyme (best fit for active site) will produce ...
1/2 Vmax at lowest Km
Higher Km means
Km describes ...
the affinity of an enzyme for its substrate
A low Km means ...
that the enzyme holds the substrate tightly (high affinity) and is very efficient at converting it to product
A high Km means
that the enzyme holds the substrate more loosely (lower affinity) and is less efficient at converting it to product
- small non-protein molecules
- Usually inorganic (metals) ions (prosthetic groups) such as Mg2+, Ca2+, Cu2+, Mn2+, Zn2+, Fe2+3+
- sometimes organic
- NAD+, CoA, Vitamins
Enzymes can only catalyze reactions that are ...
- ultimately "downhill"
- ie. where delta G is negative