BCHM 3050 1st Edition Lecture 10Outline of Last Lecture I. Mad Cow PrionsII. Fibrous Proteins III. CollagenIV. Globular Proteins – Myoglobin vs. HemoglobinV. Oxygen Binding Equilibrium CurvesVI. Effects of pH on Oxygen BindingOutline of Current 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. LigasesCurrent LectureI. Enzymesa. Enzymes facilitate the reaction but they don’t participateb. Not altered in process or consumedc. Come out of reaction unaltered and go on to facilitate another reactionII. Introductory Terminologya. Substrates - reactants (left side of the equation)b. Products – right side of the equationc. Active site of the enzyme receives the substratesThese 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.d. Transition state – intermediate form; it has properties of both the substrate and the product; supplies energy (point where the highest energy is present)III. Models for Enzyme Actiona. Enzymes are not as rigid as one thought (Lock & Key)b. They are much more flexible and dynamic (Induced Fit)c. Induced fit has been confirmed by X-ray crystallographyIV. Energy Changes During the Progress of a Reactiona. Activation Energy is the amount of energy required to reach the transition state threshold for a chemical reaction.b. Free energy is the difference in energy between the products vs. reactants.c. Measuring how fast the reaction is happening and forming a productd. Reactions could still occur without enzymes but it would take a lot longer and more energye. Substrate has more energy than the product (exothermic reactions)f. Activation energy – energy requires to get G1 to the transition state; which is much lesser when an enzyme is presentg. Enzymes lower the activation energy, but they do not alter the amount of energy in the substrate and product (different in free energy between the substrate and the product does not change)V. Six Classes of Enzymesa. Oxidoreductasesi. LEO – Lose of Electrons is Oxidationii. GER – Gain Electrons is Reductioniii. OH is oxidized in the reactioniv. Most oxidation-reduction reactions have co-factors (like NAD+, which is getting reduced in this reaction)v. Occurs when consume too much alcohol à damages the liversvi. Acetaldehyde is toxic & damages the livervii. Acetaldehyde dehydrogenase produces acetyl-CoAb. Transferasesi. Transfer a functional group from one molecule to anotherii. Ex: Phosphate group from ATP is added to Glucosec. Hydrolasesi. Water chops molecules into different parts (breaks down the molecule)ii. Water must be present!iii. Breaks down one into manyiv. Present in snake venomv. Snake venom is a neurotoxin!d. Lysasesi. Breaks down a molecule (removes part of a molecule) in the absence of waterii. Hydrolase is similar but needs water to break down the moleculee. Isomerasesi. Molecule is converted to its isomerii. See two molecules with a double headed arrow between themiii. No water present, nothing breaking off, etc. iv. Shift phosphate group from one position to anotherf. Ligasesi. Join two molecule togetherii. Ligases usually function in the presence of ATPiii. Break down ATP à
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