Biochemistry Flashcards
trypsin
cleaves C-terminal of Arg + Lys (basic AA)
chemotrypsin
cleaves C-terminal of AROMATIC AA’s
oxioreductases
redox reactions, oxidize
usually electron carriers NAD+
transferases
transfer/move functional groups
hydrolases
break down compound using H2O
lyases
cleave molecule WITHOUT H2O
isomerases
rearrange bonds
eg. move double bonds
ligases
addition/synthesis reactions between LARGE subunits
eg. nucleic acid ligase
cofactors
small inorganic or metal ions
coenzymes
small ORGANIC groups
may be vitamins/derivatives
eg. NAD+, biotin
Kcat
rate when enzyme is fully saturated
“turnover rate”
substrates turned / unit time (for each enzyme)
high Kcat = high V
UNCHANGED by changes in [substrate]
michaelis menten plot
[s] vs velocity of rxn
v = {Kcat [E] [S]} / {Km + [S]}
high Kcat = high V
high Km = low V
Km
measure of enzymes affinity for substrate
HIGH Km = LOWER affinity
hills coefficient
- cooperative binding measure
- Hill’s > 1 = positive cooperative
- Hills < 1 = negative cooperative
- Hills = 0 not cooperative
lineweaver burke plot
inverse of michaelis menten
Y intercept = 1/Vmax
X intercept = 1/Km
so lower Vmax = Y intercept is higher, higher Km = X intercept is closer
competitive inhibition
- binds to active site
- Km = INCREASES
- Vmax = SAME
- only one where Vmax doesn’t change, can be overcome by high [S]
noncompetitive inhibition
- binds to allosteric site
- Km = SAME
- Vmax = DECREASES
mixed inhibition
- binds to allosteric site
- Km = increase OR decrease
- Vmax = DECREASES
homotropic regulation
- Homotropic regulation is when a molecule serves as a substrate for its target enzyme and as a regulatory molecule of the enzyme’s activity.
- O2 is a homotropic allosteric modulator of hemoglobin.
- The four subunits of hemoglobin bind to oxygen cooperatively
suicide inhibition
- ONLY TYPE that is irreversible
- Suicide inhibition occurs when an enzyme binds the inhibitor (structurally a substrate analogue) and forms an irreversible complex with it, usually through a covalent bond
