1 Amino Acids, Proteins, and Enzymes Enzymes Enzyme Action Factors Affecting Enzyme Action Enzyme Inhibition.

Download 1 Amino Acids, Proteins, and Enzymes Enzymes Enzyme Action Factors Affecting Enzyme Action Enzyme Inhibition.

Post on 30-Dec-2015

213 views

Category:

Documents

1 download

TRANSCRIPT

  • *Amino Acids, Proteins, and EnzymesEnzymesEnzyme ActionFactors Affecting Enzyme ActionEnzyme Inhibition

  • *Program ObjectivesList 6 common features of enzyme action.Describe the role of the active site.Draw an energy diagram and identify the substrates, products, activated complex and activation energy.Describe and explain the sensitivity of enzymes to heat and pH.Identify mechanisms by which an enzyme may reduce the activation energy for a reaction.

  • *Enzymes are the working unit of an organism. Every chemical reaction that occurs in an organism is made possible by a specific enzyme.A cup of sugar left undisturbed for twenty years changes very little. However when you eat sugar, it rapidly undergoes chemical change. Enzymes account for the differences in the rate of change

  • *EnzymesCatalysts for biological reactionsMost are proteinsLower the activation energyIncrease the rate of reactionActivity lost if denaturedMay be simple proteinsMay contain cofactors such as metal ions or organic (vitamins)

  • *Proteins that catalyze (Speed up) reactions.

  • *Energy of Activation is necessary to convert the molecule to its products.Potential Energy

  • *Enzymes lower activation energy increasing the rate of the reaction.

  • *Ways enzymes speed reactions*increase the frequency of successful collisions*improve the orientation between colliding substrates*provide a new reaction path with a lower activation energyWarp and weaken a bondProvide a favorable electronic environment weakening bond

  • *Enzymes are sensitive to environmental change.temperaturechanges shape of active sitepHchanges shape of active siteenzyme concentrationsubstrate concentrationinhibitors

  • *Cofactors:An ion or molecule that must be associated with an enzyme for the enzymes proper functioning.

    Several large organic molecules, called coenzymes, serve as cofactors.

    FAD, NAD & NADP, are examples.

  • *Name of EnzymesEnd in aseIdentifies a reacting substancesucrase reacts sucroselipase - reacts lipidDescribes function of enzymeoxidase catalyzes oxidationhydrolase catalyzes hydrolysisCommon names of digestion enzymes still use inpepsin, trypsin

  • *Learning Check E1Match the type of reaction with the enzymes:(1) aminase(2) dehydrogenase(3) Isomerase(4) synthetase

    Converts a cis-fatty acid to trans.Removes 2 H atoms to form double bondCombine two molecules using ATPAdds NH3

  • *Enzyme Action: Lock and Key Model An enzyme binds a substrate in a region called the active siteOnly certain substrates can fit the active siteAmino acid R groups in the active site help substrate bindEnzyme-substrate complex formsSubstrate reacts to form productProduct is released

  • *

  • *Lock and Key Model

    + +

    E + S ES complex E + PS P P S

  • *Enzyme Action: Induced Fit Model Enzyme structure flexible, not rigidEnzyme and active site adjust shape to bind substrateIncreases range of substrate specificityShape changes also improve catalysis during reaction

  • *The binding of the substrate to the enzyme alters the structure of the enzyme, placing some strain on the substrate and further facilitating the reaction

  • *Enzyme Action: Induced Fit Model

    E + S ES complex E + PS P P SS

  • *Learning Check E2The active site is(1) the enzyme(2) a section of the enzyme(3) the substrate

    B. In the induced fit model, the shape of the enzyme when substrate binds(1) Stays the same(2) adapts to the shape of the substrate

  • *Solution E2The active site is(2) a section of the enzyme

    B. In the induced fit model, the shape of the enzyme when substrate binds(2) adapts to the shape of the substrate

  • *Factors Affecting Enzyme Action: TemperatureLittle activity at low temperatureRate increases with temperatureMost active at optimum temperatures (usually 37C in humans)Activity lost with denaturation at high temperatures

  • *Factors Affecting Enzyme ActionOptimum temperature

    ReactionRate

    Low High Temperature

  • *Factors Affecting Enzyme Action: Substrate ConcentrationIncreasing substrate concentration increases the rate of reaction (enzyme concentration is constant)Maximum activity reached when all of enzyme combines with substrate

  • *Factors Affecting Enzyme ActionMaximum activity

    ReactionRate

    substrate concentration

  • *Factors Affecting Enzyme Action: pHMaximum activity at optimum pHR groups of amino acids have proper chargeTertiary structure of enzyme is correctNarrow range of activityMost lose activity in low or high pH

  • *Factors Affecting Enzyme Action

    ReactionRateOptimum pH

    3 5 7 9 11pH

  • *Learning Check E3Sucrase has an optimum temperature of 37C and an optimum pH of 6.2. Determine the effect of the following on its rate of reaction(1) no change (2) increase (3) decrease A. Increasing the concentration of sucroseB. Changing the pH to 4C. Running the reaction at 70C

  • *Solution E3Sucrase has an optimum temperature of 37C and an optimum pH of 6.2. Determine the effect of the following on its rate of reaction(1) no change (2) increase (3) decrease A. 2, 1 Increasing the concentration of sucroseB. 3 Changing the pH to 4C. 3 Running the reaction at 70C

  • *Enzyme InhibitionInhibitors cause a loss of catalytic activityChange the protein structure of an enzymeMay be competitive or noncompetitiveSome effects are irreversible

  • *Competitive InhibitionA competitive inhibitorHas a structure similar to substrateOccupies active siteCompetes with substrate for active siteHas effect reversed by increasing substrate concentration

  • *Noncompetitive InhibitionA noncompetitive inhibitorDoes not have a structure like substrateBinds to the enzyme but not active siteChanges the shape of enzyme and active siteSubstrate cannot fit altered active siteNo reaction occursEffect is not reversed by adding substrate

  • *Effect of Inhibitors

  • *Effect of Activators

  • *Learning Check E4Identify each statement as describing an inhibitor that is (1) Competitive (2) Noncompetitive

    A. Increasing substrate reverses inhibitionB. Binds to enzyme, not active site Structure is similar to substrateD. Inhibition is not reversed with substrate

  • *Solution E4Identify each statement as describing an inhibitor that is (1) Competitive (2) Noncompetitive

    A. 1 Increasing substrate reverses inhibitionB. 2 Binds to enzyme, not active siteC. 1 Structure is similar to substrateD. 2 Inhibition is not reversed with substrate

  • *Active Site Summary

    *is usually a crevice or pocket on the protein*formed with only a few of the enzymes amino acids*changes its shape in response to the substrate

  • *The active site is a region where an enzyme molecule is folded in the shape of a crevice or cleft and where a particular reaction is catalyzed

  • *The substrate is a specific molecules that an enzyme can chemically recognize, bind to briefly, and modify in a specific way.

  • *Enzymes are specific only catalyzes one reactionActive site is complementary shape to the substrate affected.

  • *Reaction SpecificityAn enzyme always puts out the same kind of product when fed a given substrate.

  • *Enzymes perform simple reactions.isomerization rearrangement of moleculesexchange transfer of atomsaddition put two substrates togetherdecomposition change substrate into two products.

  • *Things enzymes do NOT do.*Enzymes dont make anything happen that would not eventually happen on its own, They just make it happen faster -- at least a million times faster, usually. *Enzymes do NOT initiate the reaction.*Enzymes do NOT Provide energy.LIGHT provides activation energyOR INETIC ENERGY is the activation energy.

  • **Enzymes are not used up in a chemical reaction.

    *Enzymes do have a working lifetime and eventually do break down.

    *Enzymes are not permanently altered in a reaction.

  • *7. The enzyme is NOT changed in the reaction.

  • *Allosteric Regulators

  • *Commercial Uses of EnzymesSome Non-Food Enzyme Uses Enzyme Industry Purpose or Action

    Proteases

    Detergent

    Laundry Aid

    Environmental

    Reduction of proteins in sewage treatment

    photography

    Recovery of silver from scrap film

    Glucose Oxidase

    Clinical-Analytical

    Diabetes test (glucose)

Recommended

View more >