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42 Cards in this Set
- Front
- Back
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Enzymes |
Lower activation energy Does NOT change delta G or Keq |
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6 Enzyme Categories |
Oxidoreductase Transferase Hydrolase Lyase Isomerase Ligaseq |
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Oxidoreductase |
Redox reactions |
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Transferase |
Ex. Amino transferase - Kinase: Phosphate added somewhere from an ATP |
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Hydrolase |
Split water to split a compound; opposite of condensation reaction. - Phosphotase: Removes phosphate |
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Lyase |
Breaks compound into 2 WITHOUT using water - Reverse rxn is synthase |
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Isomerase |
Reactions between isomers. An Isomerase can also be another class of enzyme |
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Ligase |
Catalyzes addition/synthesis rxns of larger molecules - contrasted with lyase/synthase which is generally for smaller molecules |
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Cofactors/coenzymes |
are NOT proteins |
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Coenzyme |
Small/organic; generally vitamins or vitamin derivative |
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Cofactors |
Small/inorganic molecules and ions |
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Water soluble vitamins |
Vitamin B (1-3, 5-7, 9, 12) and Vitamin C |
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Fat Soluble Vitamins |
Vitamins A, D, E, K |
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Apoenzyme |
Enzyme WITHOUT coenzyme - I am apalled that you have no co |
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Holoenzyme |
Enzyme WITH coenzyme - You are whole with your co |
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Prosthetic group |
when enzyme and coenzyme are tightly bound together |
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Vitamin B1 |
Thiamine |
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Vitamin B2 |
Riboflavin |
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Vitamin B3 |
Niacin |
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Vitamin B5 |
Pantothenic Acid |
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Vitamin B6 |
Pyridoxal Phosphate |
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Vitamin B7 |
Biotin |
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Vitamin B9 |
Folic Acid |
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Vitamin B12 |
Cyanocobalamin |
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Enzyme: Max Saturation |
Means it is at V max as well |
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Enzyme: V max |
It is an asymptote; there is no corresponding [S] for Vmax. Thus, [S] @ 1/2 V max = Km |
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Michaelis-Menten Equation |
V = (Vmax[S])/(Km+[S]) @ 1/2 Vmax, Km = [S] |
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Km |
Km is the substrate concentration at which half of the active sites of the enzyme are filled. - A higher Km means a lower affinity because you need more of a substrate to occupy the same amount (half) of the active sites. Vice versa |
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Lineweaver-Burk |
X-intercept = -1/Km Y-intercept = 1/Vmax |
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Enzyme Cooperativity |
Occurs when there are multiple subunits/active sites - Has a low affinity (high Km) Tense-State (T) and a high affinity (low Km) Relaxed-State (R) Go over the party analogy |
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Enzyme Activity
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AKA rate and velocity |
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Enzyme: Temperature relationship |
Typically enzyme velocity doubles every 10 degrees Celsius when moving towards the optimal temperature (98.6 F, 37 C in human body). Rapidly denatures past this point. Obviously there are exceptions. |
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Enzyme: pH relationships |
Optimal body pH: 7.4, AKA physiologically neutral If pH is less than 7.35, acidemia Exceptions: Stomach enzymes (pH 2), Pancreatic enzymes in small intestines (pH 8.5) |
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Enyzme Regulation: Feedback |
Product inhibits earlier enzyme in process |
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Enzyme Regulation: Feed-Forward |
Enzyme regulated by preceeding intermediates |
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Reversible Inhibition |
Competitive Noncompetitive Mixed Inhibition Uncompetitive Inhibition |
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Competitive Inhibition |
Competition for Active Sites - Can be overcome by increasing [S] - does NOT change Vmax because increased [S] will out-compete the inhibitor - increases enzyme Km bc you need more [S] for 1/2 occupancy of active site Lineweaver-Burk: Same y-intercept, decreased x-intercept |
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Noncompetitive |
Does NOT compete for active sites Binds equally well to the Enzyme and the Enzyme-Substrate Complex Can NOT be overcome by increasing [S] Km is constant bc the same number of active sites are still occupied at the same [S] Decreases Vmax because there is less "reactable" enzyme available Lineweaver-Burk: Same x-intercept, increased y-intercept |
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Mixed Inhibition |
Contrasted with noncompetitive Inhibitor has differing affinities for the enzyme and the E-S complex - If inhibitor bonds more readily to enzyme: lowered enzyme affinity -> increased Km - If inhibitor bonds more readily to E-S: increased enzyme affinity -> decreased Km |
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Uncompetitive Inhibition |
Allosteric Only binds to E-S complex, locking substrate into enzyme so no product can be formed Because substrate is locked in, affinity is increased -> decreased Km. No product is formed so decreased Vmax Parallel curves on Lineweaver-Burk |
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Zymogens |
Contains both a catalytic domain and a regulatory domain The regulatory domain is a sheath |
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-ogen |
Enzymes ending in -ogen (pepsinogen, trypsinogen) Are generally dangerous if left unmonitored Typically digestive enzymes |
