L12-enzyme-substrate interactions

what is enzyme kinetics

it tells us how fast a reaction occurs which is helpful when understanding disease processes

it also describes absorbance of drugs into cells by active transport

many clinical test also depend on measuring the activity of enzymes

we can also determine the potency of drug we come across

what is catalysis

the process/ steps between the forming of an enzyme- substrate complex and enzyme- product complex

after the product is made and released what does the enyme do

it can either just go on to bind with more substrates, or the active sites residues ionisation state needs to be changed or the enzyme needs to go through a large conformational change

what assumptions are made in the simple models of enzyme behaviour

• one molecule of one substrate binds to the enzyme ( which is usually rare )

• the enzyme and substrate form an enzyme-substrate complex which is the rate limiting step

• enzymes convert substrate to product and the is product released fast

• products bind weakly to the enzyme

what is the michaelis menton equation 

• at low substrate concentration the rate increases with increasing substrate rate ( first order 

• at high substrate concentrations the rate doesn’t increase with further increases in substrate concentration ( zero order )

what are the assumptions made in the steady-state model

• the concertation of the enzyme is less than the substrate

• that the substrate concentration remains constant ( initial rate )

• that the enzyme- substrate concentration remains the same throughout the reaction ( theres a balance between the making the ES and the enzyme-substrate and breaking)

• product binds weakly to the enzyme

• there’s no backwards reaction

what is Km

• the substrate concentration when the enzyme is working at half its maximum speed/ 0.5 vmax

• its often used as a measure of how tightly an enzyme binds with the substrate

• low km= enzyme bins tightly ( high affinity )

• high km= enzyme binds loosely to the substrate low affinity

• its a measure of efficiency

what does kcat mean 

this tells us how many substrate molecules one enzyme molecule can convert ito a product per second when its working at full speed 

the  formula is kcat= vmax/enzyme concentration 

its a measure of efficiency 

what is the way of measuring efficiency of an enzyme

kcat/vmax