chemistry 121(01) winter 2009

Chp. 21-1Chemistry 121 Winter 2009 LA Tech

Introduction to Organic Chemistry and BiochemistryIntroduction to Organic Chemistry and Biochemistry Instructor Dr. Upali Siriwardane (Ph.D. Ohio State) E-mail: [email protected] Office: 311 Carson Taylor Hall ; Phone: 318-257-4941;Office Hours: MTW 9:00 am - 11:00 am; TR 9:00 - 10:00 am & 1:00-2:00 pm.December 19, Test 1 (Chapters 12-14)January 2 Test 1 (Chapters 15-16)February 6 (Chapters 17-19)February 27, (Chapters 20 & 22)March 2, 2009, Make Up Exam:Bring Scantron Sheet 882-E

Chemistry 121(01) Winter 2009


Chapter 21. Enzymes and Vitamins Chapter 21. Enzymes and Vitamins

SectionsSections


Chapter 21. Enzymes and VitaminsChapter 21. Enzymes and Vitamins

21.1 General Characteristics of Enzymes21.2 Nomenclature and Classification of Enzymes21.3 Enzyme Structure21.4 Models of Enzyme Action21.5 Enzyme Specificity21.6 Factors That Affect Enzyme Activity21.7 Enzyme Inhibition21.8 Regulation of Enzyme Activity: Allosteric Enzymes21.9 Regulation of Enzyme Activity: Zymogens21.10 Antibiotics That Inhibit Enzyme Activity21.11 Medical Uses of Enzymes21.12 Vitamins21.13 Water-Soluble Vitamins21.14 Fat-Soluble Vitamins


Chapter 21. EnzymesChapter 21. Enzymes

Nomenclature and Classification

Activation Energy

Enzyme-Substrate Interaction

Cofactors and Coenzymes

Effect of pH and Temperature

Regulation of Enzyme Activity


BiologicalBiological CatalystsCatalysts

Typically very large proteins

Permit reactions to to “go” to conditions that the body can tolerate

Can process millions of molecules per second

Are very specific-react with one or only a few types of molecules (substrates).


Enzyme NomenclatureEnzyme NomenclatureNaming is easy compared to other organic compounds

Name is based on: -What it reacts with

-how it reacts

-add -ase- ending

Examples

lactase

enzyme that reacts with lactose

pyruvate decarboxylase

remove carboxyl group from pyruvate


Classification of EnzymesClassification of Enzymes

• Oxidoreductases: catalyze oxidation-reduction. • Transferases: transfer of functional groups. • Hydrolases: catalyze hydrolysis reactions.• Lyases: catalyse the removal of chemical groups.• Isomerases: catalyze isomerization reactions.• Ligases: catalyze formation of chemical bonds, join two

molecules


Effect of Enzyme on Activation EnergyEffect of Enzyme on Activation Energy

•Enzyme change howa reaction will proceed.

•This reduces the activation energy

•It makes it easier


Effect of Enzyme on Activation Energy


Effect of Substrate ConcentrationEffect of Substrate Concentration

• For non-catalyzed reactions

Reaction rate increase with concentration• Enzyme catalyzed reactions

Also increase but only to a certain point

VVmax max Maximum velocity

At VVmaxmax, the enzyme is working as fast as it can


Effect of Substrate ConcentrationEffect of Substrate Concentration


Characteristics of Enzyme Active SitesCharacteristics of Enzyme Active Sites

• Catalytic siteCatalytic siteWhere the reaction actually occurs.

•Binding siteArea that holds substrate in proper place.

Enzyme uses weak, non-covalent interactions to hold the substrate in place based on alkyl (R) groups of amino acids.

Shape is complementary to the substrate and determines the specificity of the enzyme.

Sites are pockets or clefts on enzyme surface.


Steps in Enzymatic ReactionsSteps in Enzymatic Reactions• Enzyme and substrate combine to form a complex• Complex goes through a transition state

-which is not quite substrate or product• A complex of the enzyme and the product is produced• Finally the enzyme and product separate

All these steps are equilibriaAll these steps are equilibria

Lets review each stepLets review each step


The PlayersThe Players


Formation of Enzyme-substrate ComplexFormation of Enzyme-substrate Complex


Formation of the Transition StateFormation of the Transition State


Formation of the Enzyme-Product ComplexFormation of the Enzyme-Product Complex

chemistry 121(01) winter 2009

Documents