The Wonderful World of Proteins

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The Wonderful Worldof Proteins

• Types of Proteins
• Amino Acids
• The Peptide BondProtein Structure

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Types of Proteins

• Type Examples
• Structural tendons, cartilage, hair, nails
• Contractile muscles
• Transport hemoglobin, myoglobin
• Storage milk, nuts, seeds
• Hormonal insulin, growth hormone
• Enzyme catalyzes reactions in cells
• Protection immune response

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Amino Acids

• Building blocks of proteins
• Carboxylic acid group
• Amino group
• Side group R gives unique characteristics
• R side chain (variable)
• I
• H2NC COOH
• I
• H

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Examples of Amino Acids

• H
• I
• H2NC COOH
• I
• H glycine
• CH3
• I
• H2NC COOH
• I
• H alanine

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Types of Amino Acids

• Nonpolar
• Polar
• Polar/Acidic
• Polar/ Basic

Amino acids each have their own unique chemical
properties. Some dissolve in water some do not.
This is essential for transport and storage.
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Essential Amino Acids

• 10 amino acids not synthesized by the body
• arg, his, ile, leu, lys, met, phe, thr, trp, val
• Must obtain from the diet
• All in diary products
• 1 or more missing in grains
• and vegetables

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The Peptide Bond

• Bond formed by the COOH of an amino acid and
  the NH2 of the next amino acid
• O CH3
• 
  
• NH3CH2COH H3NCHCOO
• O CH3
• NH3CH2C NCHCOO
• peptide bond
• H

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Peptides

• Amino acids linked by peptide bonds
• Gly Lys Phe Arg
  Ser
• H2N- -COOH
• end Peptide bonds end
• Glycyllysylphenylalanylarginylserine

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Protein Structure

• Primary and Secondary Structure
• Tertiary and Quaternary Structure
• Protein Hydrolysis and Denaturation

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Primary Structure of Proteins

• The particular sequence of amino acids that is
  the backbone of a peptide chain or protein

Ala-Leu-Cys-Met
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Secondary Structure Alpha Helix

• Three-dimensional arrangement of amino acids with
  the polypeptide chain in a corkscrew shape
• Held by H bonds Looks like a coiled telephone
  cord

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Secondary Structure Beta Pleated Sheet

• Polypeptide chains are arranged side by side
• Hydrogen bonds form between chains
• Typical of fibrous proteins such as silk

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Secondary Structure Triple Helix

• Three polypeptide chains woven together
• Typical of collagen, connective tissue, skin,
  tendons, and cartilage

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Tertiary Structure

• Specific overall shape of a protein
• Examples of cross links between R groups of amino
  acids in chain
• disulfide SS
• ionic COO H3N
• H bonds CO HO
• hydrophobic CH3 H3C

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Globular and Fibrous Proteins

• Globular proteins Fibrous proteins
• spherical shape long, thin fibers
• Insulin Hair
• Hemoglobin Wool
• Enzymes Skin
• Antibodies Nails Spider web

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Quaternary Structure

• Proteins with two or more chains
• Example is hemoglobin
• Carries oxygen in blood
• Four polypeptide chains
• Each chain has a heme group to
• bind oxygen

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Protein Hydrolysis

• Break down of peptide bonds
• Requires acid or base, water and heat
• Gives smaller peptides and amino acids
• Similar to digestion of proteins using enzymes
• Occurs in cells to provide amino acids to
  synthesize other proteins and tissues

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Hydrolysis of a Dipeptide
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Denaturation

• Disruption of secondary, tertiary and quaternary
  protein structure by
• 1. heat/organics
• 2. acids/ bases
• 3. heavy metal ions
• 4. agitation
• Basically the protein is unfolded without
  changing the primary structure resulting in the
  protein changing its physical properties.

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Examples of Denaturation

• Frying or boiling an egg
• Ironing or curling your hair
• Alcohol on cuts to denature proteins in bacteria
• Cooking food to denature proteins in bacteria