MCB 2610: Exam 3 pt. 7

2 kinds of enzyme inhibition

competitive inhibitor and noncompetitive inhibitor

competitive inhibitor

directly competes with binding of substrate to active site

noncompetitive inhibitor

binds enzyme at site other than active site and changes enzymes shape so that it becomes less active

effectiveness of an inhibitor has to do with what?

the affinity of an enzyme with inhibitor

there can be instances where there's high affinity to inhibitor vs. substrate due to difference in?

bulkiness of structures

one way to overcome competitive inhibition is?

increase amount of natural substrate which increases the likelihood if enzyme coming into contact with natural substrate

sulfa drugs block pathway for?

folic acid synthesis

you want to target?

pathways that bacteria cells have and we don't

low km = ?

high affinity

does an enzyme change the amount of free energy?

no

does an enzyme convert a non-spontaneous rxn into a spontaneous one?

no

noncompetitive inhibition induces?

conformational change

example of a noncompetitive inhibitor

heavy metals

3 major mechanisms of metabolic regulation

metabolic channeling, regulation of the synthesis of a particular enzyme and direct stimulation or inhibition enzyme

metabolic channeling is used more heavily in?

eukaryotic cells

in metabolic channeling you can?

move things around and compartmentalized

metabolic channeling

differential localization of enzymes and metabolites

compartmentation

differential distribution of enzymes and metabolites among separate cell structures or organelles

we associate compartmentation more with?

eukaryotes because we have more places to move things around

compartmentation can generate marked variations in?

metabolite concentrations

metabolic channeling allows us to operate different pathways?

simultaneously

metabolic channeling allows us to regulate transport of products from?

one pathway to another

eukaryotic organism folic acid catabolism is in?

mitochondria

eukaryotic organism folic acid is synthesized in?

cytosol

post-translational regulation of enzyme activity - 2 important reversible control measures

allosteric regulation and covalent modification

majority of regulatory enzymes used what reversible control method?

allosteric regulation

non-competitive inhibitors are a type of?

allosteric regulation

allosteric regulation is actively altered by?

small molecule

allosteric effector

binds noncovalently at regulatory site

allosteric effector changes shape of?

enzyme and alters activity of catalytic site

a positive effector?

increases enzyme activity allowing natural substrate to bind

a negative effector?

inhibits the enzyme

if a natural substrate neets an allosteric effector to bind with enzyme will it work without it? (example of a positive effector)

no

covalent modification of enzymes acts as an?

on/off switch for enzyme

covalent modification adds or removes?

functional/chemical groups

by covalently modificating something it?

changes activity of enzymes itself

advantages of covalent modification

respond to more stimuli in varied and sophisticated ways and regulation of enzymes that catalyze covalent modification adds second level

covalent modification glutamine synthetase of E. coli - made up of?

12 different subunits

glutamine synthetase is fully functional without?

adenylyl groups

glutamine synthetase in off when?

all 12 adenylyl groups are on

feedback inhibition is also called?

end product inhibition

why is it called end product inhibition?

when cells don't used end product the pathway to make it will get inhibited

inhibition of one or more critical enzymes in a pathway regulates?

entire pathway

pathway always regulates?

pacemaker enzyme

pacemaker enzyme is usually the?

1st enzyme in pathway

pacemaker enzyme catalyzes?

the slowest or rate-limiting reaction in the pathway

when a pathway shuts down does it shut down forever?

no only until end product concentration dies down

each end product in feedback inhibition regulates?

its own pathway and the initial pacemaker enzyme

if you see a branch point what does it mean?

it is another site for shutting down pathway

what happens if you there is a buildup of end product P but not end product Q?

end product P can shut down its own pathway without shutting down end product Q's pathway