substrate binding Flashcards
metabolic chemistry reactions:
nucleophilic substitution
swap functional groups
metabolic chemistry reactions:
nucleophilic addition
add functional groups
metabolic chemistry reactions:
carbonyl condensation
change number of carbons
metabolic chemistry reactions:
elimination
change (increase) bond order
metabolic chemistry reactions:
oxidation-reduction
move electrons
oxidoreductases
move electrons (redox rxns)
activated carriers/coenzymes of oxidoreductases
NADH, NADPH, FADH2, FMNH2
building blocks of NADH and NADPH
vitamin B3 and adenine
functions of NADH and NADPH
carry a single electron (follow the H+)
building blocks of FADH2 and FMNH2
vitamin B2 (and adenine)
functions of FADH2 and FMNH2
carry two electrons (follow the H’s)
transferases
move a functional group (group transfer)
activated carriers/coenzymes of transferases
ATP, pyridoxal phosphate, SAM, tetrahydrofolate, 5’-deoxyadenosylcobalamin
functions of ATP and pyridoxal phosphate
transfer phosphate group
in ATP, usually the gamma phosphate is removed, but the beta + gamma phosphates can be removed as
pyrophosphate
functions of SAM, tetrahydrofolate, 5’-deoxyadenosylcobalamin
transfer methyl group
building blocks of ATP
adenosine
building blocks of pyridoxal phosphate
vitamin B6
building blocks of SAM (S-Adenosylmethionine)
methionine and adenine
vitamine B9
folic acid
what vitamin contains a metal (cobalt)
vitamine B12
hydrolases
break a chemical bond by adding water across it (hydrolysis)
isomerases
rearrange order of atoms in a molecules (isomerization)
lyases
break a chemical bond without using water
ligases
paste 2 pieces together (make a chemical bond), uses ATP
activated carriers/coenzymes of ligases
TPP, CoASH, lipoamide, biotin
building blocks of TPP (thiamine pyrophosphate)
vitamin B1 + 2 phosphates
function of TPP
paste 2 groups together through an aldehyde group
building blocks of CoASH (Coenzyme A)
vitamine B5 + adenine
building blocks of lipoamide
fatty acid derivative + lysine
function of CoASH and lipoamide
paste 2 groups together through an acyl group
what vitamin is B7
biotin
function of biotin
paste 2 groups together through CO2
the active site is only a few
residues out of the protein
the active site determines substrate specificity by
size and charge complementarity
the active site makes contacts with the substrate through what type of interactions
noncovalent
allosteric binding
doesn’t occur at the active site but follows the same interaction rules as an active site
involves a second substrate/ligand which can be an activator or an inhibitor
competitive inhibitor
inhibitor binds to active site blocking substrate
allosteric inhibitor
inhibitor binds to allosteric site, changing conformation of active site, preventing substrate from binding
allosteric activator
activator binds to allosteric site, changing conformation of active site, allowing substrate to bind
apoenzymes
incomplete
inactive
lack cofactor/coenzyme
holoenzyme
whole
active
contain cofactor/coenzyme
KD definitions
dissociation constant for E * Sn complexes
breaking apart
equal to the concentration of ligand where 1/2 the available binding sites are full
when the receptor is half-saturated
KA definitions
affinity or association constant
coming together
Hill equation
Y = [S] / KD + [S]
Y = 0
means no ligand bound
Y = 1
means receptor is saturated
Y = 0.5
means receptor is half-saturated
cooperativity
binding of each subsequent ligand influences the affinity (strength of interaction) of the next ligand to bind an active site
nH = 1
no cooperativity
sites are independent
nH > 1
positive cooperativity
affinity increases
nH < 1
negative cooperativity
affinity decreases
in catabolic rxns, dehydrogenases oxidize their substrate and use
NAD+
in anabolic rxns, reductases reduce their substrate and use
NADPH