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45 Cards in this Set
- Front
- Back
definition. the maximum velocity of reaction that a particular amount of enzymes could possibly give
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Vmax
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is vmax extensive or intensive?
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EXtensive. The more the enzyme the more higher the vmax
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is Km extensive or intensive
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INtensive. enzyme concentration does not change Km
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what is inversely related to the binding affinity of the enzyme for substrate
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Km
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what does a large Km tell you
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rxn only works when substrate conc is very high
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what does a low Km tell you
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rxn will function toward vmax even at a very low concentration of substrate
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what three things could happen to the ES
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back to substrates (E+S) or forward to products (E+P)
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what is [Etotal]
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[ES] +[Efree] which simply considers all forms of enzyme going on in a reaction
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state the MM equation
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v = vmax[S]/(Km + [S])
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state the Lineweaver Burk equation
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1/v = km/vmax x 1/[s] + 1/vmax
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what is the slope of the lineweaver burk? The y intercept? the x and y axes?
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slope = km/vmax
y int = 1/vmax y axis = 1/v x axis = 1/[s] |
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what are the units of Km?
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concentration... same units as [S]
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what if Km = S
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Then v is half velocity of vmax
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what are three kinds of inhibitors?
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competitive
non competitive uncompetitive |
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where do competitive inhibitors bind? non competitive? uncompetitive?
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same site
can bind to different site on enzyme OR ES complex binds exclusively to ES |
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what changes in the MM or LB with a competitive inhibitor and why?
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vmax is the same
km apparent increases because it takes reaction longer to get there |
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what changes in the MM or LB with non competitive inhibitors?
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vmax decreases
Km stays the same |
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what changes in uncompetitive inhibition?
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kM and vmax
BUT slope stays the same! |
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what reactive groups are typically found in irreversible inhibitors?
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ser
cys |
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Finish the lecture
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Finish the lecture!
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which inhibitors usually form a covalent bond with some reactive gorup in the enzyme frequently a serine or cys at the active center
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irreversible
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what was our class example of a irreversible inhibitor
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nerve gas DFP
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what other type of inhibition do irreversible inhibitors look like
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noncompetitive
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what happens if you have an irreversilbe inhibitor that gave 50% inhibition and double it again?
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100% inactivation
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how can you overcome an irreversible inhibitor
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high substrate conc
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what is a suicide substrate
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looks like the normal substrate but when it binds it forms a covalent bond
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what three things does the reaction velocity depend on?
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catalyc speed
availability of substrate concentration of product (rate of reverse reaction) |
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define Km
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the [S] at which reaction proceeds at 1/2vmax
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what are the units of Km
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sames as the substrate concentration units
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T or F. Km depends on [enzyme] concentration
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FALSE. Km is an intensive constant
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Km is inversely relate to the affinity of an enzyme for its substrate, the higher the affinity the _____ the Km
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lower
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what would .5 units of the enzyme look like?
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define Km in terms of k1 k2 k3
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Km = (k2+k3)/k1
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state the MM equation
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State the LB equation
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Name two major classes of inhibitors
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reversible
irreversible |
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Name the three subclasses of reversible inhibitors
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competitive
non competitive un competitive |
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______ inhibitors react only with the free enzyme binding to the active site
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competitive
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what do the plots for competitive inhibitors look like?
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________ inhibitors react with the free enzyme and the enzyme substrate complex. They usually bind to a site on the enzyme surface away from the active site
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non competitive
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what do plots for noncompetitive inhibitors look like?
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_______ inhibitors only react with the substrate bound form of the enzyme
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uncompetitive
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what do uncompetitive inhibitor plots look like?
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fill in the chart
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Addition of an irreversible inhibitor will continually lower _____
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vmax
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