enzymes Flashcards
what is an enzyme
biological catalyst which speeds up a reaction
how do enzymes differ from chemical catalysts
higher reaction rates
act under milder conditions
greater specificity
can be regualtes
how are enzymes specicif
have aa in active site
properties of aa
different charges
different shapes
different pH
how does an enzyme bind to its substatea
substrate has to have the correct shape and charges in the right place to fit the active site
conformational change around the substrate
what is the transition state
highest energy point where bonds are strained
what do enzymes do to lower activation energy
stables the transition state complex
helps the bonds break in the transition states
(forms extra bonds)
why is there several peaks/troughs of activation energy
most reactions have several different transition states
Two main co factors
coenzymes
metal ions
what do coenzymes do
transfer chemical groups from one reactant to another
aid oxidation reduction reactions
what do metal ions do
coordinate negatively charged groups
i.e. prevents repulsion that would usually occur
accepte/donate e- in oxidation reduction reactions
provide charge and change shape
what is rate of enzyme reactions affected by
temperature
pH
substrate con
how does temperature affect rate
increase in vibrational energy of substrates
how does pH affect rate
causes different ionisation of functional groups leads to different charges in as
what does a low Km mean
high affinity
what dies a high Km mean
low affinity
what is Km
how much substrate is required for the enzyme to work at half its maximal rate
what is affinity
how well it binds to a substrate
what is the Michaelis menten equation
Vi = Vmax{s}/Km + [s]
what do statins compete with
HMG Co- reductase
how are enzymes regulated
allosteric interactions
covelent modification
protein protein interaction
proteolytic cleavage
how do allosteric interactions work
bind else where than AS which can alter the AS
types of allosteric interactions
homotrophic
heterotrophic
what is covalent moditifcation
regualte shape of AS
generally involved adding/removing phosphate
what is protein protein interaction
interaction leads to AS shape change
what are inactivate enzymes called once synthesized
zymogens
what do enzymes cleave off an enzyme
prodomain
what is it called when an enzyme chops iself
automatism
