Proteins and Enzymes

• Proteins have the greatest number of functions compared to other macromolecules
• There are 20 different amino acids (differ only in R groups)
• Protein monomer: Amino acid
• Amino acids are categorized as nonpolar, polar, acidic or basic based on R groups
• Dehydration synthesis links amino acids
• Hydrolysis breaks apart amino acids
• Peptide bond

  Carboxyl of one amino acid attaches to amino group of another amino acid
• Dipeptide


  2 amino acids joined together by a peptide bond
• What makes up each amino acid?

  • R group
  • Carboxyl
  • Amino
  • Central Carbon
  • Hydrogen
• Differences between amino acids is due to R group
• primary level of protein organization

  • straight chain
  • peptide bonds
• secondary level of protein organization

  • alpha helix and beta pleated sheet
  • hydrogen bonds
• tertiary level of protein organization

  • 1 polypeptide chain folded upon itself through forming a unique 3D shape
  • bonded/folded together by R-group bonds
• quaternary level of protein organization

  • 2+ polypeptide chains forming a unique 3-D shape
  • bonded/folded together by R-group bonds
• functions of proteins

  • Messenger (ex. hormones)
  • Energy storage
  • Structural
  • Immune system (ex. antibodies)
  • Enzymes
• the purpose of enzymes is to catalyze reactions. They do this by decreasing activation energy
• Induced Fit


  The enzyme will change the shape of its active site to better fit the form of the substrate.
• Lock and Key 


  The active site (lock) of the enzyme and the substrate (key) are both shaped perfectly for each other and do not need to change.
• 37 C is ideal for most enzymes excluding archaebacteria
• Heat denatures enzymes by breaking bonds, cold only slows down movement
• optimal temperature for most enzymes

  37 degrees C
• When an enzyme is denatured, its r-group bonds are disrupted and even broken.
• In acids, [H] is greater than [OH].
• In water, [H] is equal to [OH]
• In bases, [H] is less than [OH]
• pH of 1 to 7 are known as??

  Acids
• pH of 8 to 14?

  Bases
• As you go from 1 to <7, the acid gets weaker
• As you go from >7 to 14, the base gets stronger
• Where is pepsin found?

  Stomach
• Where is Trypsin found?

  
Small intestine
• What is the optimal pH for trypsin?

  pH 8-9
• What is the peak temperature for thermophilic enzymes?

  60 to 80°C
• At what temperature do enzymes denature?

  40 degrees C (104°F)
• Kinetic energy



  The energy of motion at low temperatures
• Which 2 functional groups are always found in protein monomers?

  Amino and Carboxyl
• What is the optimal pH for pepsin?

  pH 2
• At what pH do most enzymes work best at?

  Neutral (7)