Lecture 13 - Enzymes 2

Question 1

what are the factors affecting enzyme catalysed reactions?

Answer 1

substrate conc, enzyme conc, temperature, PH, inhibition, end product inhibition

Question 2

what is Vmax?

Answer 2

maximum velocity achieved by the system at saturating substrate concentrations

Question 3

what is Km?

Answer 3

substrate concentration at which the reaction velocity is 50% of Vmax

Question 4

what km means the enzyme is more efficient?

Answer 4

lower km

Question 5

what are the 5 types of enzyme inhibition?

Answer 5

reversible inhibition- competitive and non competitive
irreversible inhibition 
uncompetitive inhibition 
end product inhibition
zymogens

Question 6

what is disulfiram used for?

Answer 6

used to support treatment for severe alcoholism by producing acute sensitivity to ethanol - it inhibits aldehyde oxidases

Question 7

what is nifedipine?

Answer 7

non competitive inhibitor used as angina medication, its a calcium channel blocker which inhibits ATPase and prevents uptake of ca2+ into cardiac cells

Question 8

How do irreversible inhibitors work?

Answer 8

bind extremely tightly to the enzyme - covalently- that it can’t be removed

Question 9

what is sarin and how does it work?

Answer 9

its an irreversible inhibitor, it binds to serene residues in acetylcholinesterase preventing nerve impulse transmission

Question 10

Describe uncompetitive inhibition

Answer 10

binds to enzyme substrate complex to decrease Vmax and km, effect of this cannot be overcome by increased substrate concentration

Question 11

what is end product inhibition?

Answer 11

inhibitor in the first step of the reaction, important in control for multistep reactions

Question 12

what it a zymogen?

Answer 12

an inactive form of an enzyme, it is a longer peptide chain which must be hydrolysed ti form the active form, cleavage at the activation sites may release polypeptides known as pro-sequences and therefore results in enzyme activation