Slide1 l.jpg
This presentation is the property of its rightful owner.
Sponsored Links
1 / 22

CHE 242 Unit VIII The Structure, Properties, Reactions and Mechanisms of Carboxylic Acids and Their Derivatives CHAPTER TWENTY-FOUR PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

CHE 242 Unit VIII The Structure, Properties, Reactions and Mechanisms of Carboxylic Acids and Their Derivatives CHAPTER TWENTY-FOUR. Terrence P. Sherlock Burlington County College 2004. Structure of Proteins. =>. Stereochemistry of - Amino Acids. =>. Arginine (Arg) Threonine (Thr)

Download Presentation

CHE 242 Unit VIII The Structure, Properties, Reactions and Mechanisms of Carboxylic Acids and Their Derivatives CHAPTER TWENTY-FOUR

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Slide1 l.jpg

CHE 242Unit VIIIThe Structure, Properties, Reactions and Mechanisms of Carboxylic Acids and Their DerivativesCHAPTER TWENTY-FOUR

Terrence P. Sherlock

Burlington County College


Structure of proteins l.jpg

Structure of Proteins


Chapter 24

Stereochemistry of amino acids l.jpg

Stereochemistry of-Amino Acids


Chapter 24

Essential amino acids l.jpg

Arginine (Arg)

Threonine (Thr)

Lysine (Lys)

Valine (Val)

Phenylalanine (Phe)

Tryptophan (Trp)

Methionine (Met)

Histidine (His)

Leucine (Leu)

Isoleucine (Ile) =>

Essential Amino Acids

Chapter 24

Complete proteins l.jpg

Complete Proteins

  • Provide all the essential amino acids.

  • Examples: those in meat, fish, milk, eggs.

  • Plant proteins are generally incomplete.

  • Vegetarians should eat many different kinds of plants, or supplement diet with milk or eggs. =>

Chapter 24

Rare amino acids l.jpg

Rare Amino Acids

  • 4-Hydroxyproline, 5-hydroxylysine found in collagen.

  • D-Glutamic acid in cell walls of bacteria

  • D-Serine in earthworms

  • -Aminobutyric acid, a neurotransmitter

  • -Alanine, constituent of the vitamin pantothenic acid. =>

Chapter 24

Zwitterion l.jpg


  • Amino acid exists as a dipolar ion.

  • -COOH loses H+, -NH2 gains H+.

  • Actualstructure depends on pH. =>

Chapter 24

Properties of amino acids l.jpg

pKb = 12

pKa = 10


Properties of Amino Acids

  • High melting points, over 200C

  • More soluble in water than in ether.

  • Larger dipole moments than simple acids or simple amines.

  • Less acidic than most carboxylic acids, less basic than most amines.

Chapter 24

Structure and ph l.jpg

Structure and pH


Chapter 24

Isoelectric point l.jpg

Isoelectric Point

  • pH at which amino acids exist as the zwitterion (neutral).

  • Depends on structure of the side chain.

  • Acidic amino acids, isoelectric pH ~3.

  • Basic amino acids, isoelectric pH ~9.

  • Neutral amino acids, isoelectric pH is slightly acidic, 5-6. =>

Chapter 24

Electrophoresis l.jpg



Chapter 24

Reaction with ninhydrin l.jpg

Reaction with Ninhydrin

  • Used to visualize spots or bands of amino acids separated by chromatography or electrophoresis.

  • Deep purple color formed with traces of any amino acid. =>

Chapter 24

Structure of peptide l.jpg


Structure of Peptide

  • The peptide bond is an amide bond.

  • Amides are very stable and neutral.

Chapter 24

Peptide bond formation l.jpg

Peptide Bond Formation

  • The amino group of one molecule condenses with the acid group of another.

  • Polypeptides usually have molecular weight less than 5000.

  • Protein molecular weight 6000-40,000,000. =>

Chapter 24

Classification of proteins l.jpg

Classification of Proteins

  • Simple: hydrolyze to amino acids only.

  • Conjugated: bonded to a nonprotein group, such as sugar, nucleic acid, or lipid.

  • Fibrous: long, stringy filaments, insoluble in water, function as structure.

  • Globular: folded into spherical shape, function as enzymes, hormones, or transport proteins. =>

Chapter 24

Levels of protein structure l.jpg

Levels of Protein Structure

  • Primary: the sequence of the amino acids in the chain and the disulfide links.

  • Secondary: structure formed by hydrogen bonding. Examples are -helix and pleated sheet.

  • Tertiary: complete 3-D conformation.

  • Quaternary: association of two or more peptide chains to form protein. =>

Chapter 24

Alpha helix l.jpg


Alpha Helix

Each carbonyl oxygen can hydrogen bond with an N-H hydrogen on the next turn of the coil.

Chapter 24

Pleated sheet l.jpg


Pleated Sheet

Each carbonyl oxygen hydrogen

bonds with an N-H hydrogen on an

adjacent peptide chain.

Chapter 24

Summary of structure l.jpg

Summary of Structure


Chapter 24

Denaturation l.jpg


  • Disruption of the normal structure of a protein, such that it loses biological activity.

  • Usually caused by heat or changes in pH.

  • Usually irreversible. A cooked egg cannot be “uncooked.” =>

Chapter 24

Slide21 l.jpg

Chapter 24

Slide22 l.jpg


Chapter 24

  • Login