enzymes Flashcards
enzymes
protein catalysts bind substrates release products have more than one subunit cut out the opportunity to go the unctalysed way
modification of enzymes
they always return to original form: not used up by reaction
act as a point of regulation
in metabolic pathways
combined catalytic activities=control
short=energy or long-foetal dvmpt
problems
over or under expression can lead to cell dysfunction ( can be used to identify problems such s heart attacks)
Substrate-Binding Sites
Substrates bind to specific sites via interactions with enzyme’s amino acids
spatial geometry dictates specificity
active catalytic site
where the reaction occurs
different functional groups co-enzymes, metal ions, amino acid
residues
pH & Temperature Profiles:
Enzymes have a functional pH & temperature range - e.g. increased temperatures = reaction rate
but if you go too far denaturation (looses its actual functionality)
enzyme catalysed
e+s=ES=e+p
reaction equilibrium
do not alter position
accelerate it’s establishment
Lock & Key’ Model
Complementary 3-D surface that “recognises” the substrate
- substrate binds through hydrophobic, electrostatic
interactions & hydrogen bonds
- Binding can be prevented by steric hindrance (bumping in to each other)& charge
repulsion
induced-fit model
As substrates bind, enzymes undergo conformational change
side chains of amino acids
binding reactions increase
dynamic surface= can increase atp
active site
Cleft or crevice formed by polypeptide chain - 3D arrangement permits reacting substrates
to approach each other
substrate binding
conformational change
transition state
bonds become maximally strained
activation energy
difference between substrate and transition state complex enzymes decrease the activation energy
