Designed by Pyeongsug Kim ©2010 Supplemental instructionEnzymes Enzyme activityEnzyme activity Metabolic pathwaysMetabolic pathways Metabolic regulationsMetabolic regulations Picture from

-Biological catalysts; most are _________ (3D conformation). -(increase/decrease) rate of chemical reactions -Act by (lowering/rasing) activation energy of a reaction. *Activation energy ~ energy required for a reaction to proceed. Enzymes Proteins -Enzyme is (altered/unaltered) Pictures: Copyright © The McGraw-Hill Companies, Inc. Designed by Pyeongsug Kim, ©2010

-___________ into which substrates (reactants) fit. -An enzyme reacts only with (specific / nonspecific) substrate. :because of the great diversity of protein structure  allows different enzymes to be specialized in their action. Active sites Pictures: Copyright © The McGraw-Hill Companies, Inc. Designed by Pyeongsug Kim, ©2010

___________ -a location on an enzyme where a regulating molecule can attach. The regulating molecule can be a final product of a metabolic pathway. Allosteric sites Designed by Pyeongsug Kim, ©2010

_____________ Is rate its substrates are converted to productsEnzyme Activity Enzymes have optimal ___________and _______ ranges. - due to 3-D structure, changes in the conformation of enzyme or active site. temperaturepH Pictures: Copyright © The McGraw-Hill Companies, Inc. pH optimum for Enzymes - Pepsin – active in acidic(HCl); stomach (acidic). - Salivary amylase – active in neutral pH; saliva. - Trypsin – active in alkaline pH; pancreatic juice. Designed by Pyeongsug Kim, ©2010

An increase in substrate concentration (increases/decreases) the rate of product formation until enzyme is __________. saturated Pictures: Copyright © The McGraw-Hill Companies, Inc. Designed by Pyeongsug Kim, ©2010

__________ include metal ions such as Ca 2+, Mg 2+, Mn 2+, Cu 2+, Zn 2+ and selenium. Cofactor binding changes conformation of __________. __________ are derived from vitamins; transport small molecules needed by enzymes. Cofactors Coenzymes active site Pictures: Copyright © The McGraw-Hill Companies, Inc. Designed by Pyeongsug Kim, ©2010

________________ -Series of reactions, each catalyzed by a different enzyme. -The product of one reaction is the substrate for the next. -Most are branched. Metabolic pathways Pictures: Copyright © The McGraw-Hill Companies, Inc. Designed by Pyeongsug Kim, ©2010

___________________ -Occurs when 1 product in a divergent pathway inhibits activity of the branch-point enzyme -Prevents_____________________ End product inhibition final product accumulation End product of a pathway accumulates  inhibit the metabolic pathway by (positive/negative) feedback. When the end product is depleted  the pathway (resumes/stops). Designed by Pyeongsug Kim, ©2010

Regulating Enzymes 1)________________ - the final product of the metabolic pathway inhibits an earlier reaction in the sequence. Picture from Feedback inhibition 2) _______________ can bind with an enzyme's active site -involves a molecule that is not the substrate molecule but that can bind with an enzyme's active site. -no room for the substrate to bind at that site. - prevents the enzyme from carrying out the chemical reaction. Competitive inhibition Designed by Pyeongsug Kim, ©2010

3) _______________ allosteric site -A chemical molecule binds to allosteric site in the enzyme causing it to inactivate. -The molecule can be final product. -noncompetitive inhibition Allosteric inhibiton Picture from Designed by Pyeongsug Kim, ©2010

Enzyme inhibitors Enzyme inhibitors (outside body) In a Drug -Competitive Enzyme Inhibition -drugs that bind to the enzyme's active site & reduces its activity In heavy metalic Poison -heavy metals: copper, lead, mercury … Picture from In other poisons - Oak, ivy, Snake venom, insects…. - Most competitive inhibitors. Designed by Pyeongsug Kim, ©2010

Metabolic pathway Normal pathway Missing Enzyme B The result No substrate3 No substrate 4 No product!! Accumulation of substrate2 What happens if a single enzyme in a pathway is defective? Designed by Pyeongsug Kim, ©2010

Inborn errors of metabolism -Genetic diseases -involves disorders of metabolism. -Due to defects of single genes that code for enzymes that facilitate conversion of various substances (substrates) into others (products). -Newborn screening Eg. Phenylketonuria (PKU) ~ A deficiency in the hepatic enzyme which is necessary to metabolize the amino acid (protein). Picture from Designed by Pyeongsug Kim, ©2010

_______________________ are due to inherited defects in genes for enzymes in metabolic pathways. Result from (Increases/decreases) in intermediates formed prior to the defective enzyme.  lead to disease! or (increases/decreases) in products normally formed after the defective enzyme.  lead to disease! Inborn Errors of Metabolism (metabolic diseases) Designed by Pyeongsug Kim, ©2010

____________________ -require input of energy to proceed - products contain (more/less) free energy than reactants. Endergonic reactions ____________________ -release energy as they proceed - products contain (more/less) free energy than reactants. Exogonic reactions Most (exergonic / energonic) reactions in body make ATP. _____ = the universal energy carrier.ATP C 6 H 12 O 6  6CO 2 + 6H 2 O + ATP Endogonic? Exogonic ATP  ADP + Pi + energy Endogonic? Exogonic Designed by Pyeongsug Kim, ©2010

A ________ agent donates electrons or H(hydrogen) An ________ agent accepts electrons or H(hydrogen) OiL RiG Oxidation is “loss” of electrons Reduction is “gain” of electrons reduced oxidized reducing oxidizing NAD & FAD - Coenzymes that play important roles as H carriers - Vitamins -NAD+, FAD ( ) -NADH, FADH 2 ( ) Oxidized Reduced If a molecule gains electrons it is _________. If it loses electrons it is ________. Designed by Pyeongsug Kim, ©2010