Proteins

• Proteins are condensation polymers which are formed from amino acid monomers joined together by amide links (in proteins also known as a peptide link) similar to the structure in nylon

  • units in proteins are different, consisting of amino acids
• Amino acids are small molecules containing NH2 and COOH functional groups

  • R represents a different group for each amino acid e.g H, CH3

  
• There are twenty common amino acids, each differing by their side chain, represented by R

  • Proteins can contain between 60 and 600 of these amino acids in different orders
  • These are the monomers which polymerise to form the protein
• Condensation polymerisation to make protein

  A) condensation

  B) peptide link

  
• The structure of proteins can be represented using the following diagram whereby the boxes represent the carbon chains

  
• Proteins are natural polymers

  • formed from amino acid monomers
• Proteins are polyamides

  • similar to nylon
  • contain the -CONH- group aka an amide link (peptide link)
• Proteins are formed by condensation polymerization of amino acids as they contain a carboxylic group and an amine group
• There are 20 different amino acids so many different proteins can be formed
• Protein structure

  A) lost

  B) becomes water

  C) h2o

  
• Protein Structure

  A) amide links

  
• Proteins are similar to synthetic polyamides as they have the same amide link

  • differ from synthetic polyamides as proteins have many monomers whilst polyamides have 2 monomers
• Amino acids have the COOH and NH2 on the same molecule
• Polyamide monomers have 2 lots of COOH or they have 2 lots of NH2
• Hydrolysis - the process of using water to split
• Hydrolysis of the amide bond in the protein releases the individual amino acids

  • involves acid and heat
• Amino acids can be separated by chromatography
• Thin layer chromatography can be used to separate and identify the product of hydrolysis of carbohydrates and proteins

  • locating agent e.g. ninhydron is used - ensures the spots of amino acid or sugar are visible
• How many functional groups do amino acids contain?

  2
• What are the two functions groups in an amino acid?

  Amine and carboxyl