Lecture 5: functions and kinetics Flashcards
Types of cofactors
1-inorganic: metal ions
2- organic: groups derived from vitamines
acceleration of reactions catalysed by enzymes compared to non-catalysed
10^6 to 10^12 fold
enzymes are complementary to ….
transition states
catalytic mechanisms leading to enzyme functions
1- acid-base catalysis
2-covalent catalysis
3- metal ion
4- orientation based catalysis
How can proton acceptor (general bases) contribute to base catalysis
they abstract a proton making the substrate a good nucleophile
How can metal ions catalyse reactions in enzymes
1- In oxidation-reduction reactions
2-electronically shielding and stabilising negative charges
3- By providing the correct orientation
which cofactor is used in carbonic anhydrase and what is the function?
zinc ions
zinc forces the water to release a proton.
The CO2 goes to the active site and the hydride attacks CO2 producing HCO3-
What are the 6 classes of enzymes
1- oxidoreductases 2-transferases 3-hydrolyaser 4-lyaser 5-isomeraser 6-ligaser
oxidoreductases need…..
and often contain …. metal ions
Cofactors
Fe 3+/2+
Which enzyme class kinases do kinases belong to
transferases
Which catalytic mechanisms are used for peptide hydrolysis
covalent hydrolysis and acid-base catalysis
The active site of chymotrypsins can accomodate which …. side chains
aromatic
which enzyme class does adenylate cyklase belong to?
lyases
enolase belongs to
lyases (hydratase; danner vand)
Enzymer som fjerner carboxyl-grupper er…
lyases
Assumptions made in michael mentens kinetics
The rate of complex degradation is not reversible
The rate of the formation of complex is the same as the rate of the formation of reactants from the complex
The optimum pH of an enzyme is close to the pH of the …….in which the enzyme is found
environment
