Enzymes Flashcards
Enzyme types
Hydrolase Oxidoreductase Transferase Isomerase Lyase Ligase
Hydrolase
hydrolysis rxns
Oxidoreductase
redox rxns
Lyase
non-hydrolytic bond cleavage
Ligase
bond formation
Isomerase
transfer between isomer (stereo or conformational)
Transferase
transfer functional groups
Km
[S] at which v=1/2Vmax
Competitive inhibitors bind to…
active site
Competitive inhibitors bind to…
active site
E
Competitive Inhibition
Vmax = unchanged Km = increased
Noncompetitive Inhibition
Vmax = decreased Km = unchanged
Uncompetitive Inhibition
Vmax = decreased Km = decreased
Mixed Inhibition
Vmax = decreased Km = increased or decreased
Noncompetitive inhibitors bind to…
Allosteric site, cause conformational change of active site
E or ES
Uncompetitive inhibitors bind to…
Allosteric site
ES only, make complex inactive
Mixed inhibitors bind to…
Allosteric site
E or ES
Which type of inhibition can be reversed by increasing [S]?
Competitive
Enzymes ONLY affect…
reaction rate via lowering activation energy
What digestive enzyme is found in the stomach? What does it break down? What pH does it function best at?
Pepsin
proteins –> polypeptides
2
What type of cells secrete pepsinogen? What activates it into pepsin?
Chief cells
HCl
What digestive enzyme is found in the duodenum? What does it break down? What pH does it function best at?
Aminopeptidase
Cleave amino acids from N terminus
8
Peptidyl transferase is made of what? It carries out the main function of what? What is that function?
rRNA
ribosome
linking amino acids with peptide bonds
Restriction enzymes (endonucleases) carry out what function? What are they used in (body & research)?
Cut DNA at specific sites
DNA repair & southern blotting
Nucleoside-diphosphate kinase catalyzes which reaction?
ATP + GDP → GTP (+ADP)
HMG-CoA reductase aids in production of what? In what organ? What pathway is this?
cholesterol
liver
mevalonate
What is a cofactor?
non-protein chemical compound or metallic ion that is required for an enzyme’s activity
Coenzyme
small organic molecules that bind/donate groups to dependent enzymes
Inorganic cofactor
usually metal ions (Zn, Fe)
Holoenzyme
enzyme lacking its necessary cofactor
Type I restriction enzyme
remote from recognition site
require ATP & S-adenosyl-L-methionine
Type II restriction enzyme
within or at short distance from recognition site
often require Mg2+
Type III restriction enzyme
short distance from recognition sites
require ATP
Type IV restriction enzyme
modified DNA (methylated, hydroxymethylated)
Kinases catalyze…?
addition of phosphate group
According to Michaelis-Menten equation, v= ?
v = Vmax*[S] / (Km + [S])
