BIO 172 1st Edition Lecture 9Outline of Last Lecture I. Posttranslational modificationsII. ChaperonesIII. EnzymesOutline of Current Lecture I. Enzymes ContinuedII. CarbohydratesCurrent LectureEnzymes:Factors that affect the rate of a reaction: Temperature, pH, concentration of ions.Temperature affects an enzyme’s peak activity based on where that enzyme is used to living:If conditions are not right, the enzyme willnot have a fast reaction rate.If it is too cold, the enzyme cannot grab a substrate.If it is too warm, the enzyme may denature and no longer interact with the substrate.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.As the amount of substrate (symbolized as [S] for substrate concentration) increases, the rate of reaction increases! Maximum Velocity is when the enzyme and substrate are constantly reacting, so the substrate saturates the enzyme. Vmax is when an enzyme is processing a substrate to make a product as fast as it can!KM is the substrate concentration needed to get half way to Vmax.Km = measure of affinity = [S] needed to fill 1/2 active sites = [S] at 1/2 VmaxNOTE: lower Km=higher affinity!Lower Km also means the enzyme is MORE efficient! This is because less efficient enzymes needmore of the substrate so they can reach Vmax… therefore they need a higher Km to be half the Vmax! So Km is higher for less efficient enzymes that have lower affinity.The amount of enzyme in a reaction affects the rate- as the Enzyme Concentration Increases, the Velocity of the Reaction increases!Using LESS enzyme in a reaction results in a lowered Vmax… so Km will stay the same, but fewerproducts will be made in a given time.Cofactors: are additional bound molecules that support catalysis.• Inorganic cofactors are often metals (Cu2+, Zn2+, Fe2+, Mg2+, Mn2+) - requirement for trace minerals in diet. These examples of metals are cofactors, which are trace metals that associate with a protein and help it maintain its function.• Often directly interact with substrates to lower EA.• Provide enzymes with a broader range of catalytic reactionsEnzyme Regulation:Environmental factors alter enzyme regulation, such as temperature, pH, and concentration of the substrate and enzyme.These factors affect the rate of a reaction! Some environments are peak conditions for a reaction.Transcription factors turn on and off genes (regulating proteins).Substrate(glucose)Enzyme(hexokinase)When the substratebinds to the enzyme’sactive site, the enzymechanges shape slightly.This “induced fit” resultsin tighter binding of thesubstrate to the active siteIrreversible Inhibition:Covalent bonds allow an inhibitor to bind to an enzyme. This alters the conformation of the enzyme, blocking all activity.Typically the inhibitor binds to the active site.This is irreversible because cells lack an enzyme that can break this covalent bond, and therefore the enzyme stays inactive.*COVALENT BONDS ON ACTIVE SITE: IRREVERSIBLE inhibitor, which inactivates the enzyme.Specificity induces a fit between enzyme and its substrate.Reactant Molecules Bind to Specific Locations in an Enzyme.Hexokinase (enzyme)is specific to the substrate, glucose, which is what binds (above).Competitive Inhibition directly blocks the active site!A competitive inhibitor competes with the substrate, and it can trick the enzyme by taking the shape of the substrate to fit easily.Competitive inhibitors have a higher Km needed to react with the enzyme. Substrate requires less concentration, because the substrate is the properfit.The Vmax is the same for the substrate and competitive inhibitor.Many drugs are competitive inhibitors. They attach at the normal enxymebonding site (the enzyme is a qarternarystrucute).*When you add a competitive inhibitor, the Km would increase (move farther along the x axis, getting bigger because you need more substrate). The Vmax would not change!Non-Competitive Inhibitors:Do not bind to the active site- they bind to a very distinct site. But when they bind, the enzyme’s shape changes. This makes it less able to bind with the substrate.These inhibitors do not resemble the substrate!Vmax is lowered when a Non competitive inhibitor interacts with the enzyme.Allosteric.Allosteric:Allosteric regulation is when a regulatory molecule binds away from the active site. The non active site is called a regulatory site.They can inactivate or make the enzyme active by changing its conformation.They alter properties of the active site, so affecting Km and Vmax.Competitive- binds to active site, is competing with substrate.Allosteric- might allow substrate to bind more easily!Allosteric (non competitive)- changes shape of enzyme so the substrate can no longer bind!Review reactions:Exergonic: spontaneous, free energy or reactants greater than that of products. Endergonic: uphill, positive delta g, nonspontaneousCatabolic Reactions are reactions with NEGATIVE deltaG. Anabolic have Positive deltaG.Less disorder in tight chemical bonds. Through catabolism is NEG delta g, meaning catabolic reactions are spontaneous. Allows energy to be harnessed so ATP (or energy) is generated.Catabolism: breaks down largermolecule into smaller!More disorder to less, more energy to less… need to consume ATP in order to build macromolecules! Put in chemical energy to make this a negative delta g.Coupling more energy will make the reaction Spontaneous! (above picture)Carbohydrates: Monosaccharides, Disaccharides, Polysaccharides.Carbohydrates make up: Sugars, cartilage, structural support, cell walls.Amino sugars: Glucosamine (extracellar matrix of joint cartilage & chitin)Sugar phosphates (in nucleotides)Formula for Carbohydrates: (CH2O)nMonosaccharides are Simple Sugars.Disaccharides are two monosaccharide joined by a GLYCOSIDIC bond.A Glycosidic bond*: A Condensation/Dehydration reaction forms this kind of bond.Maltose (in beer), Sucrose = table sugar, Lactose = milk sugar (glucose + galactose)Fructose is a structural isomer of glucose (6 carbons but 5 sided ring; ketose instead of aldose) > sweeter than glucose*Two alpha glucoses (dehydration reaction forms covalent bond) form the alpha-glycoside link.Alpha links are best for fuel storage.*Beta linkage: beta galactose and beta glucose bond to form a rigid and hard to break bond. This beta linkage is stronger than alpha, so it is used in carbohydrate