BIOL 302 1st Edition Lecture 9Outline of Last Lecture I. Protein Sequence Determination, high resolution structure determinationOutline of Current Lecture II. Review III. O2 in Hemoglobin and MyoglobinIV. EnzymesCurrent LectureI. Some topics to review:Henderson Hasselbalch equation, pKa, buffers, pHStereoisomersStructures of all amino acids Segregation of amino acids by property (apolar, polar, charged…)Charge of amino acids dependent on pH (charge at physiological pH or calculate withthe pKa), titration curves of amino acidsPeptide bondProtein structurePrimary, Secondary, Tertiary, Quaternary structureSecondary structures such as α-helices and β-sheets, Ramachandran plotNon-covalent interactions, electrostatic, van der Waals, hydrogen bond, hydrophobicII. Clicker question: Which of the following will diminish release of oxygen from fully oxygenized hemoglobin in target tissues?A. Rigorous exerciseB. Lowered blood pH in diabetes patientC. High altitudeD. Fetal hemoglobinE .None of the aboveIII. Clicker question: Which of the following will diminish uptake of oxygen to hemoglobin in lungs? A.Half of the four hemoglobin subunits are loaded with oxygen. B. Lower concentration of 2,3-bisphospho-glycerate.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.C. High altitude D. Fetal hemoglobin E. None of the aboveIV. Clicker question: What can you NOT conclude from this graph which plots oxygen saturation of hemoglobin versus the oxygen pressure?A. At the oxygen pressure found in lungs, the pH has very little effect on oxygen saturation.B. At the oxygen pressure found in lungs, the oxygen saturation is slightly reduced by presence of CO2.C. Presence of CO2 increases oxygen uptake in lungs.D. The oxygen saturation always increases with the oxygen pressureV. The localized increase in CO2 in tissues results in formation of carbonic acid which ionizes to give bicarbonate and H+.A. CO2 + HOH <===> H2CO3 carbonic anhydraseB. H2CO3 <===> HCO3- + H+VI. The Bohr EffectA. Lowering the pH decreases the affinity of oxygen for HbVII. CO2 is also transported to lungs by carbamate formationA. Covalent binding at the N-terminus of each subunitVIII. Chemical modification triggers loss of O2 from HemoglobinA. Carbamate:1. CO2 combines with NH2 at the N-terminus of globins2. Bohr effect: lowering the pH decreases the affinity of oxygen for HbIX. Influence of CO2 and H+ on Hemoglobin Respiring Tissue LungX. Clicker question: What can you NOT conclude from this graph which plots oxygen saturation of hemoglobin versus the oxygen pressure?A. At the oxygen pressure found in tissues, a lower pH increases oxygen release.B. In tissues, CO2 increases the release of oxygen more strongly than in lungs.C. The effect of pH and CO2 on oxygen saturation is strongest at the oxygen pressure found in tissues.D. CO2 decreases oxygen saturation.XI. Clicker question: Hemoglobin has a very high affinity for oxygen in the lungs, and a lower affinity for oxygen in tissues, which leads to efficient uptake of oxygen in lungs and efficient oxygen release in target tissues. Which of the following do not contribute to this effect?A. Higher proton concentration in tissues B. Cooperative binding of oxygenC. 2,3-bisphosphoglycerate acts as allosteric effectorD. Higher blood sugar level in tissuesE. Carbamate formationXII. Clicker question: Which one is the Hill plot of myoglobin?A. B.XIII. Hemoglobin Disorders A. Normal Hb has Glu at 6. B. Sickle cell Hb has Val insteadC. Referred to as HbSD. Non-polar residue on surface of S subunits E. “Sticky” patches interact with hydrophobic pocketEnzymesChapter 8XIV. Enzymes are the major functional molecules for ALL lifeA. Almost every chemical process in the cell is catalyzed, and vast majority of catalysts are protein enzymes B. A large fraction of the total coding capacity of genome is dedicated to genes encoding enzymes.C. Many diseases are associated with altered activity of a human enzyme, or withthe unwanted activity of a viral or bacterial enzymeXV. Enzymes - Large and SmallA. As of this writing, there are 45,000 enzyme structures in the Protein Data Bank (PDB)*B. Molecular weights (Da): C. Ribonuclease, 12,640 , Lysozyme, 13,930 , Glutamine synthetase, 600,000XVI. Enzyme Classification XVII. Examples of Enzymatic Activity. Proteolytic ActivityA. A proteaseB. Catalyzes cleavage of a peptide bondXVIII. Cleavage of a Peptide BondA. Enzymatic cleavage occurs on the carboxyl side of the recognized sidechainXIX. Esterase ActivityA. Many proteases also have esterase activity and catalyze cleavage of an ester bond.XX. Some enzymes require cofactorsXXI. CofactorsA. Some enzymes require cofactors for activityB. (Apoenzyme + Cofactor = Holoenzyme)XXII. Free energy and equilibriumA. 〖∆�〗^(° )=−′ �����′B. ∆�=〖∆�〗^(° )+′ ���� ([�])/([�])C. 〖∆�〗^(° ) = free energy in the standard state for biochemical reactions (pH 7, ′25 C, H+ and H2O taken as 1)XXIII. Enzymes can accelerate chemical reactionsA. Enzymes are large biological molecules responsible for the thousands of metabolic processes that sustain life.B. Enzymes can accelerate reactions typically 106 - 1012 fold. C. Enzyme catalyzed reactions occur at physiological conditions.XXIV. Distinguishing features of enzymesA. Enzymes are extremely efficient, with 2nd order rate constants (kcat/Km) at or near the physical limits of bimolecular collision 108 to 1010 M-1 sec-1XXV. Rate Enhancement A. Formation of carbonic acid from CO2 and H2O.B. Uncatalyzed rate = 1.3 x 10-1 molecules/secC. Catalyzed rate = 1.0 x 106 molecules/secD. Rate enhancement = 7.7 x 106 times XXVI. Catalyzed vs Uncatayzed Rate A. Measure formation of product or loss of substrate with timeXXVII. Transition state theory and activation energyA. A transition state diagram is a plot of the reaction coordinate of reactants versus the free energy G.B. The transition state X╪ is the point of the highest free energy.C. The free energy of activation ∆G╪ is the free energy of the transition state less that of the reactants (A and B).XXVIII. Enzymes are catalysts and reduce the activation energyXXIX. Reaction