M2: Enzymatic Reactions Flashcards
enzymes overview
- proteins that help maintain equilibrium in the cell by accelerating (catalyzing) biological reactions
- not consumed/destroyed in reaction, so they can be detected in lab tests
- only catalyze their specific chemical reaction
naming of enzymes (usually)
“substrate - ase”
substrate
molecule that an enzyme acts upon (aka molecule going through the chemical reaction)
catalase
- increases speed of hydrogen peroxide (H2O2) decomposition into H2O + O
- protects cell from oxidative damage by reactive oxygen species (ROS)
- cell would die without it
lipase
- catalyzes lipid breakdown
- essential for metabolism in absence of glucose
protease
- catalyzes protein breakdown
- essential whenever we eat
6 major categories of enzymes
- Hydrolases
- Isomerases
- Ligases
- Lyases
- Oxidoreductases
- Transferases
Hydrolases
catalyze hydrolysis (addition of water to break chemical bonds)
Isomerases
- promote intramolecular rearrangements by changing bonds w/in molecule –> create different molecule with same formula
- eg: AB –> BA
Ligases
- cause molecules to form covalent bonds
- e.g. A + B –> AB
Lyases
- cause bonds to break w/out hydrolysis or oxidation
- e.g. AB –> A + B
Oxidoreductases
- catalyze electron transfer from reductant (electron donor) to oxidant (electron acceptor)
- e.g: A- + B –> A + B-
Transferases
- transfer a functional group from one molecule to another
- e.g: Ab + C –> A + Cb
how enzymes work (4 steps)
- substrate binds to active site on enzyme molecule
- enzyme converts substrate
- enzyme releases converted substrate
- reaction resets (enzyme can be used again)
hydrolysis
addition of water to break chemical bonds
eg: AB + H2O –> AOH + BH
reductant
electron donor
oxidant
electron acceptor
active site
chemically specific site on enzyme molecule, so that only correct substrate can bond to the enzyme, determined by amino acid composition of enzyme
