They make things, they break things

 What are some of the subjects that were covered in lecture this semester?  Which of these topics involve enzymes?  What are some of the enzymes that you discussed?

 Some enzymes you’ve learned about:  G3P dehydrogenase  ATP synthase  RNA polymerase (primase)  Ligase  DNA polymerase  Kinase (aka phosphotransferase)  Topoisomerase (a gyrase)  Aminoacyl-tRNA synthetase  And more…

 Most enzymes are globular proteins  Catalytic activity  Not used up in a reaction  What have you noticed about their names?  Often have “-ase” suffix  Often have function in name An RNase

 Ribozymes?  Some enzymes are made of RNA  Example?

 Enzymes lower the required Energy of Activation  This allows for faster reactions  This facilitates reactions that otherwise could not occur  Some enzymes can make reactions go trillions of times faster  Carbonic anhydrase (stomach) can catalyze over 1,000,000 reactions per second  Temperature versus selectivity

Progress of the reaction Products Reactants ∆G < O Transition state Free energy EAEA DC BA D D C C B B A A

Progress of the reaction Products Reactants ∆G is unaffected by enzyme Course of reaction without enzyme Free energy E A without enzyme E A with enzyme is lower Course of reaction with enzyme

 Lock and Key  Older theory  Stabilization of transition state?  Enzyme flexibility?  Induced Fit  Preferred method of explanation

Substrate Active site Enzyme Enzyme-substrate complex (b)(a)

Enzyme Products are released. Products Substrates are converted to products. Active site can lower E A and speed up a reaction. Substrates held in active site by weak interactions, such as hydrogen bonds and ionic bonds. Substrates enter active site; enzyme changes shape such that its active site enfolds the substrates (induced fit). Active site is available for two new substrate molecules. Enzyme-substrate complex Substrate

 Enzymes often catalyze only a single reaction  Enzymes are typically very specific

 Both enantiomers protonated to make effective proton pump inhibitors  Esomeprazole displays lower first-pass hepatic metabolism and slower plasma clearance

 Enzymes can be inhibited by compounds  Inhibitor often similar in structure to substrate  Enzymes can be inhibited at active site or a different part of the molecule  Allosteric inhibition  Enzymes can be activated at allosteric sites

(a) Normal binding (c) Noncompetitive inhibition (b) Competitive inhibition Noncompetitive inhibitor Active site Competitive inhibitor Substrate Enzyme

 NSAIDs  Non-steroidal anti-inflammatory drugs  Examples include: Ibuprofen, Rofecoxib, Acetylsalicylic acid  Inhibit COX-2 enzyme (cyclooxygenase-II)  COX-2 involved in synthesis of prostaglandins, which are involved in inflammation and pain

 Non-protein chemical required for activity of protein  Many vitamins are cofactors  E.g., Iron, Manganese, Zinc  Cofactor functions  Assist with chemical reaction  Mg 2+ and Taq  Allow protein to fold  E.g., zinc fingers

 First (often) enzyme in a biosynthesis pathway is an allosteric enzyme  Multiple binding sites  Binding to effector changes conformation

Enzyme 1 Enzyme 2 Enzyme 3 Inter- mediate Inter- mediate Product Start of pathway Presence of product inhibits enzyme 1 X Also known as feed-back inhibition

 Enzyme that oxidizes a substrate to form light  luciferin + O 2 → oxyluciferin + light  Utilized by multiple organisms  Fishes, fungi, copepoda, shrimps, algæ, and more

 Reporter genes  Various assays  Forensics

 eIoiM eIoiM  Short  Nac Nac  Long