BCHM 3050 1st Edition Lecture 11Outline of Last Lecture I. EnzymesII. Introductory TerminologyIII. Models for Enzyme ActionIV. Energy Changes During the Progress of a ReactionV. Six Classes of Enzymesa. Oxidoreductasesb. Transferasesc. Hydrolasesd. Lysasese. Isomerasesf. LigasesOutline of Current Lecture I. How does liquidy syrup inside candies form?II. Substrate Concentration has the Greatest EffectIII. Initial Velocity is FastestIV. Importance of Vmax and KmV. Significance of KmVI. Experimental Determination of Vmax and KmVII. The Michaelis-Menton EquationVIII. Lineweaver-Burk PlotsCurrent LectureI. How does liquidy syrup inside candies form?a. Invertase (enzyme) makes candies more creamy than granular; more liquidy thansolid.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.b. Breaks down sucrose into glucose and fructose to keep it a syrup consistencyII. Substrate Concentration has the Greatest Effecta. Need substrate for enzyme to react’ more reactants = better acting enzyme b/c more substrates for it to bind tob. Velocity – rate of enzyme functionc. Enzyme will not exceed it pre-set maximum velocityd. Vmax = Rmax= the maximum possible velocity that a reaction can havee. Vmax/2 = half-maximum velocity of reaction that corresponds to Km constant in substrate concentrationf. Km = how well a substrate and an enzyme reactIII. Initial Velocity is Fastesta. Dashed line = excellent, ideal enzyme (but doesn’t exist b/c all enzymes function plateau)b. Rate of the very beginning of the graph is the initial velocity (the closer to a straight line, the better the enzyme)c. Substrate concentrations gradually decreased. Reaction velocities slow down with timee. Reverse reaction starts to occurf. Initial velocities are the most relevantIV. Importance of Vmax and Kma. Both are constants that help define enzymesb. Rarely operate at true Vmax (not always enough substrates to get substrate to its full potential)i. Substrate concentration in cells is not usually high enoughii. Substrate at Km is more realisticc. Most enzymes work at half of their Vmax (at Km)d. Km is an indication of enzyme affinity for substrateV. Significance of Kma. The lower the Km, the better the enzyme (lowers the Vmax which decreases the energy needed for the enzyme to function at its best)b. Lower Km à enzyme will bind tighter to the substrate; graph will be more hyperbolicc. Fructose has higher substrate affinity because it has a lower Km, lower Vmax, functions betterVI. Experimental Determination of Vmax and Kma. Above graph allows estimation of Vmax& Km.b. Estimations would be easier if working with a straight linec. Lineweaver-Burke plots are linear transformations of hyperbolic plots.VII. The Michaelis-Menton Equationa. Leonor Michaelis and Maud Menten developed the hyperbolic relationships and their equation in 1907.b. Michaelis-Menton equation can be used to predict the velocity of a reaction at a given substrate concentration (assuming you know the the Km &Vmax constants).c. V = [Vmax x [S]]/[[S] + Km]VIII. Lineweaver-Burk Plotsa. Lineweaver& Burk developed their double-reciprocal plot in 1934.b. - Reciprocal of Michaelis-Menton equation is a slightly better way of representingitc. V = [Vmax x [S]]/[[S] +
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