Enzymes Flashcards
define the rxn: nucleophilic substitution
swapping of functional groups
define the rxn: nucleophilic addition
addition of functional groups
define the rxn: carbonyl condensation
change # of carbons
define the rxn: elimination
change (increase) bond order
define the rxn: oxidation-reduction
move electrons
how do we know oxidation/reduction occurred in a redox rxn?
follow the e-s as it carries the H. OIL RIG
oxidoreductases are what type of rxn?
oxidation-reduction
transferases are what type of rxns?
group transfer
hydrolases are what type of rxns?
hydrolysis rxns ie break a chem bond by adding h20
lyases are what type of rxns?
Break a chem bond w/oo using h20
isomerases are what type of rxns?
isomerization ie rearrange order of atoms in a molecule
ligases are what types of rxns?
Use ATP to piece 2 pieces together ie make a chem bond
what are the coenzymes fo oxidoreductases?
NADH, NADPH, FADH2, FMNH2
what is the vitamin precursor for NADH and NADPH
B3 niacin (nicotinate)
what group does the coenzymes for oxidoreductases carry?
electrons
what is the vitamin precursor for FADH2 and FMNH2?
b2 (riboflavin)
ribitol is a reduced form of _
ribose
what is the enzyme for the coenzyme NAD?
lactate dehydrogenase
what is the enzyme for the coenzyme flavin adenine nucleotide?
monoamine oxidase
what are the coenzymes for trasnferase: transfer of a phosphate group?
ATP, pyridoxal phosphate
the carrier molecule ATP (in its active form) carries what group?
phosphoryl
what are the coenzymes for trasnferase: transfer of a methyl group?
SAM, tetrahydrofolate, and 5’deoxyadenosylcobalamin
for the conezyme pyridoxal phoshate, what is the enzyme?
glycogen phasphorylase
what is the vitamin precursor for tetrahydrofolate
Folate B9
the group carried by tetrahydrofolate?
one-carbon units
SAM is the primary _ donor in cells
methyl
what is the enzyme for coenzyme tetrahydrofolate?
thymidylate synthase
what is the enzyme for coenzyme 5’-deoxyadenosylcobalamin
methylmalonyl mutase
hydrolases _ a chemical bond by _ h20 across it
break by adding h20
isomerases _ order of atoms in a molecule
rearrange
lyases _ a chem bond _ h20
break without h20
ligases use _ to _ a chem bond
use ATP to make a chem bond
what are the coenzymes with +/- aldehyde group?
TPP
what is the vit precursor for TPP?
B1
what is the enzyme for coenzyme TPP?
pyruvate dehydrogenase
what are the conenzymes for +/- an acyl group?
CoAsh and lipoamide
what is the vit precursor for CoAsh
B5 (pantothenate)
what are the building blocks for lipoamide
a fatty acid derivative and lysine
what is the enzyme for coenzyme A
acetyl CoA carboxylase
for +/- CO2, what is the coenzyme?
biotin
what is the vit precursor for biotin?
B7 biotin
what is the conenzyme for coenzyme biotin
pyruvate carboxylase
the active site is only a few residues out of the protein, t/f?
true
the active site is 3D pocket creating a unique _
microenvironment
the active site determines substrate specificity by __
size and charge complimentary
the active site contacts with the substrate through __ interactions
non-covalent ie temporary
a receptor just binding a __
just binding a protein (ligand)
an enzyme-substrate not only binds to target substrate but also
does something with what we bind
allosteric binding occurs where
does not occur at the active site
allosteric binding involves a 2nd substrate which can be a _ or a _
activator of inhibitor
how does an allosteric inhibitor fcn
inhibitor binds to allosteric site and changes protein active binding site so substrate no longer binds; build up of unbound substrate
how does an competitive inhibitor fcn
inhibitor looks close enough to actual substrate and able to fit in the active binding site for it
how does an allosteric activator fcn
conformational change of enzyme causes rxn to be halted bc of its incorrect shape. activator binds and changes to correct shape so substrate can bind and rxn can continue
holoenzymes are whole and active and contain _
cofactor/coenzyme that are allosteric activators
apoenzymes are incomplete and inactive and lack __
cofactor/conenzyme
when Y =0
no ligand bound
when Y =1
receptor is saturated
when Y = 0.5
receptor is half saturated ; kD =[S]
what is cooperativity
binding of each subsequent ligand influences the affinity of the next ligand to bind
nH=1
no cooperativity (sites are independent)
nH is greater than 1
positive cooperativity (affinity increases)
nH is greater than 0 but less than 1
negative cooperativity (affinity decreases) ie next ligan is even more difficult to bind