Enzymes Flashcards
enzymes: structure and function
- proteins that catalyze rxns
- most are globular
enzymology
- first enzyme discovered: diastase
first enzyme isolated: urease
general properties of enzymes: rates
- accelerate rxn rates
- accomplish rate accelerations at mild conditions
- pH 7, 37 C°
general properties of enzymes: capacity for regulation
- allosteric control
- covalent modification
- enzyme synthesis
general properties of enzymes: rxn specificity
selectively recognize proper substrates
absolute specificity
only catalyze one rxn
relative specificity
catalyze one type of rxn
stereochemical specificity
catalyze certain isomers
general properties of enzymes: classifications
according to rxn types
oxidoreductase
transfer of hydride or H
transferase
group transfer
hydrolase
hydrolysis (functional groups –> water)
lyase
cleavage of C-C, C-O, C-N, leaving double bonds or rings
isomerase
group transfer to yield isomeric forms
ligase
form C-C, C-S, C-O, C-N by condensation, coupled to cleavage with ATP
cofactors
augment ability of enzymes to catalyze
organic cofactor
coenzyme
inorganic cofactor
essential ion
cofactor: apoenzyme
inactive, enzyme devoid of cofactor
cofactor: haloenzyme
active, enzyme with cofactor
relationship: [E] to V0
- constant [S]
- linear
- first order in E
- rate = K[E]
relationship: [S] to V0
- constant [E]
- first order in low [S], zero order in high [S]
- high [S], V0 = K
michaelis-menton equation
V0= Vmax[S]/[S] + Kd
[S]«Km
Vmax/Km * [S]
first order in [S]
[S]»Km
V0=Vmax
zero order in [S]
