Week 5- Enzymes Flashcards
catabolic pathways?
breaking down (glucose broken down for energy) requires energy
anabolic pathways?
synthetic pathways (synthesis of glucose from amino acids) requires energy
what is exergonic?
reactions release free energy
reactants are like a ball rolling down a hill
catabolism, generates disorder
delta G <0, spontaneous reaction
what is endergonic?
reactions consume free energy
reactants are like a ball going up a hill
anabolism, order increases
delta G >0, non-spontaneous reaction
how is activation energy reduced?
enzymes (catalyst)
final equilibrium and delta G don’t change
what are the 3 basic steps of enzyme catalysts?
1- binding of substrate
2- conversion of bound substrate to bound product
3- release of product
done in the active site of the enzyme
how do enzymes work?
- they have a specific active site that binds the substrate
- can change the shape of the substrate to facilitate product formation
- bind cofactors (coenzymes that also facilitate substrate change) can be metal ions or organic molecules
- stretch bonds in substrate molecules, making them unstable and more reactive to the action of other substrates
what is acid-base catalysis?
enzyme side chains transfer H+ to or from the substrate causing a covalent bond break
what is covalent catalysis?
a functional group in a side chain bonds covalently with the substrate
what is metal ion catalysis?
metals on side chains loose or gain electrons
first law of thermodynamics?
in energy conversion the total energy remains constant (enthalpy)
no energy is created or lost in conversion
second law of thermodynamics?
universe tends towards disorder (entropy)
which way is the reaction going to shift with a negative delta G?
right (forward)
which way is the reaction going to shift with a positive delta G?
left (reverse)
what does delta G do?
- mechanical work (muscles)
- transport work (carrier proteins)
- biochemical work (makes molecules)
- thermogenesis (ATP oxidation, heat)
- energy from fuel oxidation (NADH, FADH)
Apoenzymes?
lacking cofactors
Haloenzymes?
have cofactors
what functional group does NAD accept?
hydride ions from lactate
what functional group does FAD accept?
2 electrons as 2 hydrogen atoms
oxireductases?
catalyze oxidation and reduction reactions
dehydrogenases: transfer hydrogen between a substrate and a coenzyme (NAD, FAD etc)
transferases?
kinases?
transfer a specific functional group from the donor molecule to the acceptor molecule
transfer phosphate from ATP to a second substrate
hydrolases?
hydrolysis reaction where bonds (CO, CS, CN) are cleaved by the addition of water
eg, digestive enzymes and lysosomal enzymes
lyases?
carboxylases?
cleaving bonds in another way other than hydrolysis or ox- reduction
eg, aldolase, thiolases
carbon lyases that remove or add carboxyl group from organic compounds
isomerases?
can convert a molecule from one isomer to another
eg, mutase catalyzes the shifting of a functional group from one position to another within the same molecule
ligase? (synthetases)
synthesize bonds (CO, CS, CN, CC) in reactions couple to the cleavage of a high energy phosphate bond in ATP eg, DNA ligase
units for Vmax?
km?
umol/min/mg
mM
when do enzymes have high affinity for their substrate?
at low substrate concentrations
does glucosekinase have a high or low affinity for a substrate?
low affinity for glucose so it requires a higher glucose concentration to function
reversible inhibition?
competitive inhibition?
- inhibitor binds non-covalently to the active site and prevents substrate from binding
- competitive inhibition, if substrate concentration is increased than the substrate will bind to the active site
- this increases the Km but no effect on Vmax
uncompetitive inhibitor?
- allosterically binds to the enzyme substrate complex and prevents the complex from releasing substrate
- it cannot be surmounted
- increasing the inhibitor will lower Vmax
non-competive inhibitor?
- binds to the enzyme allosterically, changes shape and alters the active site
- decreases the amount of active enzyme and reduces Vmax
irreversible inhibitor?
inhibitor binds covalently to the active site and permanently inactivates the enzyme
allosteric regulation?
effector molecule that binds to a regulatory subunit inducing the enzyme to change its shape
- can inhibit or activate the enzyme
allosteric enzymes?
- have multiple active site
- sensitive to low concentrations of inhibitors, important in regulating the entire metabolic pathway
non- allosteric enzymes?
- have one active site
- small changes in activator concentration can promote large changes in the reaction
what are isozymes?
- different form of the same enzyme
- catalyze the same reaction but have different properties (temperature)
- organisms can use to adjust temperature changes
what happens to enzymes at high temperature?
non-covalent bonds break, loose its tertiary structure and is denatured
what enzymes measure liver damage?
and for cardiac damage?
aspartate and alanine aminotransferases
creatinine kinase
Beers Law?
the amount of light absorbed by a compound in a solution is directly related to the concentration of the compound in solution
activation transfer coenzymes?
participate in catalysis by binding with a substrate
oxidation reduction coenzymes?
do not form covalent bonds with the substrate
cystic fibrosis?
Cl- secretion and secretion of water and other ions is impaired
this alters the pH and dehydrates secretions that participate and obstruct the lumen = causing inflammation and degradation of the pancreas, liver, gall bladder, intestine.
pancreatitis?
inflammation of the pancreas
caused by high levels of amylase (break down starch) and lipase (digest fats) in the blood stream
