Enzymes Flashcards
What are the two models that explains Enzyme substrate binding
Induced-Fit model
Lock and Key model
What are the two subclasses under Co factors
Metal Ions
Co enzymes
What are the two subclasses of Co enzymes
Co substrates
Prosthetic groups
Whats the difference between Cosubstrates and Prosthetic Groups
Prosthetic groups are tightly bound to the enzyme where as Co substrates are transient andd bind only when needed
What are the two types of Enzymes that require Metal ions as co factors
Metalloenzymes and
Metal-activated enzymes
What are the difference between Metalloenzymes and metal activated enzymes
Metalloenzymes have tightly bound metal ion cofactors where as metal-activated enzymes are activated by metal-ion cofactors
What converts a zymogen into its active form
The cleavage or removal of a polypeptide segment from the protein
What is saturation kinetics of enzymes
This is when There is an increase in the substrate concentration but there is no increase in Initial velocity
Hence the enzyme has reached a point where theyre saturated with the substrate
What is the michaelis Menten constant(Km)
The concentration of the substrate required to reach half of Vmax
What does a high Km mean
The enzyme has a low affinity for its substrate
What is Enzyme inhibition
Altering the kinetic parameters of an enzyme catalyzed reaction by an inhibitor
What are the two broad categories of enzyme inhibition
Reversible Inhibition
Irreversible inhibition
What are the types of reversible Enzyme Inhibition
Competitive Inhibition
Noncompetitive Inhibition
Uncompetitive Inhibition
On the double reciprocal plot for competitive inhibition, what are the key factors on the graph
Vmax remains unchanged
But Km increases
Usually how are competitive inhibitors able to bind to the same active sites as the substrates
theyre usually structural analogues of the the substrates
Give examples of Competitive inhibitors and the Enzymes they inhibit
Methotrexate-Dihydrofolate reductase(prevents production of Tetrahydrofolate in DNA synthesis in bacteria)
Sulfanamides - PABA(Also affect Folate synthesis in bacteria)
Statin drugs - HMG CoA Reductase(Prevent the synthesis of Cholestrol)
In Non competitive inhibiton Describe the key features of the Double reciprocal Graph
The Vmax decreases
But the Km remains the same
Give an example of a non-competitive inhibitor and the enzymeit inhibits
Non-nucleoside Reverse Transcriptase inhibitor(Nevirapine)- viral enzyme HIV-1 reverse transcriptase
Heavy metal poisoning- makes enzyme inactive
WHich type of Inhibitor only binds to the Enzyme substrate complex after it has been formed
Uncompetitive inhibitor
what are the key features of The double reciprocal plot of Uncompetitive inhibition
The Vmax Decreases
Km decreases
What are the two types of Irreversible inhibitors
Covalent
Suicide inhibitors
Give an example of a covalent inhibitor
Di-isopropyl fluorophosphate(DIPF)- inhibition of acetylcholinesterase
