Week 4 Post 1

Video 1
-Enzymes are a specific type of protein 
-Enzymes are the potential targets of drugs
-Enzymes are catalysts for the reactions they facilitate 
-an enzyme+substrate yields and enzyme substrate. That is a reversible reaction
-the enzyme substrate can turn to enzyme + product when the product is released
-rate substrate concentration graph 
-V max is a theoretical maximum that requires infinite concentration of substrate
-as substrate concentration increases, the rare increases in a logarithmic fashion
-1/2 V Max is a special value. Concentration required to get 1/2 Vmax is called the michaelis constant 
-michaelis constant is a concentration 
-V=(Vmax•[S])/Km+[S]
-called michaelis-menten equation. 
-it's a hyperbolic shape
-difficult to match data to function bc in early 1900s didn't have data software
-a linear equation was needed
-1/V=(Km/Vmax)•(1/[S])+(1/Vmax)
-this is a linear equation that uses reciprocals. Lineweaver-berke equation
-all to model rate v [S]
Video 2
-that was all for a normal enzyme, but drugs are meant to mess up the behavior 
-3 types of reversible inhibitors: competitive inhibitors, non competitive inhibitors, and uncompetitive inhibitors.
-competitive inhibitors are the main kind
-inhibitors bind to the enzyme at the same spot as a substrate
-gets in way of substrate and can't bind to make products
-it's a competitive process for the active sight
-as you add inhibitors, the hyperbolic graph begins to flatten out, and looks to slow the rate dramatically 
-V max is not changed, just requires more concentration to get to same levels as before
-even with inhibitors, with a lot of concentration of Substrate, you can still overwhelm the inhibitors
-Km value is pushed to a larger value
-as Km increases affinity drops
-affinity is how much an atom binds to for something
-Non competitive inhibitors bind to enzyme not on the active sight
-binds to allosteric sight
-can bind both enzyme and enzyme+substrate, as it sienta compete for active site
-interferes with operation of the enzyme trying to form a product
-curves look similar but Vmax is lowered so the curves are not as tall
-Km values stay the same
-affinity is unchanged
-Uncompetitive inhibitor only bonds to enzyme+substrate complex
-Vmax decreases, and Km decreases
-shows curve were the bottom is actually in front of the original curve but is a lot shorter and levels out faster
-competitive inhibiting is important because of you know the substrate of the enzyme, the structure of the inhibitors and substrate should be similar
-irreversible inhibitors are shunned by medicine bc they chemically bond to enzymes and therefore could bind to other proteins too
-in last 5-10 years, people are looking at irreversible inhibitors more
Video 3
-IC50 is an inhibitor conc. That is required to reduce the rate of a substrate conversion by 50%
-requires tests to be performed
-graphed with rate and the log of inhibitor conc.
-with little to no inhibitors, the rate is high
-as you reach a certain conc, it drops off significantly, and the graph is a sigmoidal type plot
-the point where the graph has most change (point of inflection) is at 1/2 Vmax
-the place where log of inhibitor is at inflection, is the log IC50
-these 50s are the amount of a compound to get 50% of the effect
-shows how well the inhibitor inhibits
-Ki is another way, and it's an equilibrium constant
-technical term for how well an inhibitor binds to an enzyme
-Km (observed)=(Km/Ki)•[I]+Km
-In y=mx+b form
-when inhibitor is 0, the Km is the normal Km of the reaction
-as inhibitors are added, Km increases
-affinity is decreased 
-slope of line is Km/Ki
-Cheng-prussoff equation lets you go back and forth between Ki and IC50

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