Lecture 2/12

• zwitter ion capability of proteins gives a buffering capability
• application of antigenicity of proteins is development of assay
• proteins

  • classification
  • simple proteins - yield only amino acids on hydrolysis
  • conjugated proteins - both protein and nonprotein parts
• apoprotein - protein portion of a conjugated protein
• prosthetic group - non-protein portion of conjugated protein
• we name proteins by their prosthetic group

  • e.g. metalloprotein - hemoglobin, ferritin
  • e.g. glycoprotein - haptoglobin
  • e.g. lipoprotein - triglycerides/cholesterol "LDL/HDL"
• ferritin - stores iron, prevents oxidative damage
• triglycerides/cholesterols are specific lipids which act as prosthetic group for lipoproteins
• metabolism/synthesis of proteins

  • proteins are put together as a result of DNA template in cells
  • DNA unwinds, separates, creates RNA template
  • RNA template moves to ribosome, polypeptide is created
  • polypeptide moves to ER, where it's modified
  • smooth ER may add components
  • Golgi apparatus sorts similar proteins and sends it to destination
• Metabolism/synthesis of proteins

  • creation of proteins is stimulated or inhibited by hormones
  • most plasma proteins are synthesized in liver and secreted into circulation
  • exception - immunoglobulin is secreted by plasma cells
• hydrolysis is breaking apart molecules using water
• catabolism of proteins

  • half life of proteins can vary from hours to years
  • shortest lived proteins include some plasma proteins
  • longer lived proteins include fibrous (structural proteins) e.g. collagen
• process of deamination involved removing amino group

  • this amino group, now ammonia, is converted to urea
  • ketoacid remains
  • incorporated into glucose/fat
• prealbumin and albumin

  • travel the fastest on electrophoresis
  • closest to end
  • lightest
• a-1 globulins and a-2 globulins

  • second closest to end
• B-globulins

  • third closest to end
• y-globulins

  • migrate backwards on electrophoresis
• at a pH of 8.6, all proteins will have a net negative charge
• basic protein electrophoresis - travel from negative to positive