EXAM 2 Flashcards
What is a catalyst?
- something that increases the rate (speed) of reaction\
- but does not under go any permanent chemical change as a result
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- but does not under go any permanent chemical change as a result
What do postive, negative and zero values mean in the gibbs energy equation?
How does delta G change when a reaction is or isnt at equilibrium?
What are ways in which an unfavorable reaction completes
What is the difference between a transition state and an activation energy state?
What are ways where an activation energy barrier can be overcome?
- Raise the temperature
- stablize the transition state (via enzyme)
What is the induced fit model?
- When a substrate binds the enzyme chages shape so that the subsrate is forced into the transition state
- accomplished via four strategies
- substrate orientation
- Straining of substrate bonds
- creating a favorable microenvironment
- covalent and/or noncovalent interacions between enzyme and substrate
What is covalent cataylsis?
- actual definition
- enzyme covalently binds the transition state (eletron transfer)
- strategy that involves covalent interactions between enzyme and substrate
What is acid base catalysis?/
- actual def
- Partial proteon transfer to the substrate
- noncovalent interactions between the enzyme and substrate
What is approximation (Catalysis strategy) ?
Remember, binding occurs in three dimensions
if eletrons and /or proteins must be exchanged, proper spatial orientation and close contact (proximity) of the reactant molecules must occur
If both pieces of the puzzle are captured and held in the proper orientation right net to each other, they are more likely to react with one and other (also known as entropy reduction)
What is eletrostatic catalysis?
stabilization of unfavorable charges on the transition state by polarizable side chains in the enzyme and/or metal ions
Why do we need proteases?
Recycling
regulation
defense
What are the qualities of chymotrypsin?
- the active site is an example of catalytic triad (repersented by yellow streaks)
- serine (S195) = a nucleophile
- Histidine (H57) = a base (proteon acceptor)
- Aspartic Aaid (D102) = an acid (proton donor)
- N terminus becomes the alkoxide ion
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Oxyanion hole stablizes the tetrahedral intermediate (transition state)
- serine (S195)
- glycine (G193)
- Specitiy (S1) pocket determines placement of cut
- At asp 189 = trypsin
- at val 216 or val 190 = elastase
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What purposes do carbonic anhydrases serve?
- physiology releveance
- pH regulation
- Enzyme pathway regulation
- Medical application
- artifical lungs
- industrial application
- CO2 scrubbers for reduction of greenhouse gases
What are qualities for the carbonic anhydrases?
- The active site contains a ZN++ ion
- coordinated to 3 histadines and a water
- H2O facilitates the transition state
- deprontonated
- catalytic strategy of aproximation
- Entry channel determines size of substrate
- co2 is small and weakly polar
What is the reaction mechanism for Carbonic Anhydrases
- Water bind to Zn++, lowering pKa. At physiological pH, water loses a proton
- Catalytic strategy of approximation as subsrate enters
- Nucleophillic additions (add functional group to CO2_
- Release of product and regeneration of enzyme (histadine proteon shuttle)
what are the three kinestic trends possible ?
What are characteristics of a reaction rate of an irreversible reaction?
What is teh reaction rate for a reversible reaction?
What is the michaelis menten kinetics model and various varibles associated with it?
What is the michaleis mention equation and special applications of it?
What is the specificity constant and what can it tell you about your enzyme?
true of false: Michaelis-mentin kinetics can be used to describe multiple binding sites but as long as their cooperative.
what can the lineweaver-burk plot tell you?
true or false: Inhibtors must be reversible.
False; they can both reversible and irreversible
What are the three types of Reversible inhibition?
- Use nonocvalent interactions to bind
- results in
- Competitive
- Noncompetitve
- allosteric
- Uncompetitive
- allosteric
What are characteristics of competitive inhibition?
What are characteristics of Non-competitive inhibition?
What kind of inhibiton is this?