Pre-mat enzymes Flashcards
Hydrolase
catalyze a hydrolytic cleavage reaction
nuclease
breaks down nucleinc acids by hydrolyzing bonds between nucleotides
protease
breaks down proteins by hydrolyzing peptide bonds between AAs
ligase
joins two molecules together
isomerase
catalyzes rearrangement of bonds within a single molecule
polymerase
catalyzes polymerization reactions
kinase
catalyzes addition of phosphate groups to molecules
phosphatase
catalyzes the hydrolytic removal ofa phosphate group
oxio-reductase
catalyze reactions in which one molecule is oxidized while other is reduced (oxidase, reductase, dehydrogenase)
ATPase
hydrolyzes ATP
Holoenzyme
Apoenzyme/conenzyme
Apoenzyme/metal ion
APoenzyme/prosthetic group
a biochemically active compound formed by the combination of an enzyme with a coenzyme
- non-preotein oragnic substance which is dialyzable, thermostable, loosely attached to apoE (CoA, FAD, NAD) (help with redox and activation-transfer rxns)
- tightly bound (help with electron transfers)
- oragnic substance which is firmly attached to apoenzyme (heme)
Lineweaver-Burk plot
1/V = Km/Vmax * 1/[S} + 1/Vmax
y axis: 1/V
x axis: 1/[S]
x intercept: -1/Km
y intercept: 1/Vmax
slope: Km/Vmax
Km
the concentration of substrate which permits the enzyme to achieve half Vmax
Enzyme cooperativity
Hill equation/coefficient
changes the sigmoidal-ness of binding curve, more cooperative makes more significant vertical part of sigmoid
1> negative cooperative
1= no coop
1< coop
Michaelis-Menten
V= Kcat [Enzyme] [S] / (Km + [S])
shows that reaction velocity (y) related to substrate concentration (x) and there is a Vmax that levels out at
Km= concentration of substrate to reach 1/2 vmax
Reversible inhibition: competitive inhibition
binds to active site of enzyme and prevents substrate binding
CHANGES Km (x intercept) OF LINEWEAVER BURK
Reversible inhibition: non-competitive inhibition
binds to inside or outside the active site resulting in inability of substrate to bind
CHANGES Vmax (y intercept) of LINEWEAVER BURK
Reversible inhibition: un-competitive inhibition
affects both Vmax and Km of lineweaver burk plot!
Irreversible inhibitors
Mechanism based:
- reactive inhibitors (suicide inhibitors) substrate analogs that form covalent bonds with AA side chains in active site
- transition state analogs- structure resembles the transition state of the natural substrate
alkylating agents: modify essential cysteine resideus
Heavy metals bind cysteine residues
medically important
isozymes
each of two or more enzymes with identical function but different structure
ex. hexokinase isoforms: 1, 2, 3, glucokinase
tissue specific, differential regulation, subcellular localization differs
