post lab disc

• what makes up the amino acids?

  carboxyl group, amino group, R group
• 2 types of proteins

  simple and conjugated
• 2 types of proteins based on native conformation

  globular or fibrous
• globular

  spherical (ex. albumin)
• fibrous

  elongated (ex. gelatin)
• Treatment added to egg albumin: HEAT and 95% ETHANOL

  give:

  • evidence of denaturation:
  • factor that causes denaturation:
  • coagulum formation
  • heat
• Treatment added to egg albumin: 10% AgNO3 & 10% CuSO4

  give:

  • evidence of denaturation:
  • factor that causes denaturation:
  • ppt formation (AgNO3 = white ppt), (CuSO4 = light blue ppt)
  • heavy metals
• Treatment added to egg albumin: HELLER'S TEST & ROBERT'S TEST

  give:

  • evidence of denaturation:
  • factor that causes denaturation:
  • reagent:
  • ppt by ring (white ring ppt)
  • strong mineral acids
  • Heller's: conc HNO3, Robert's: MgSO4.7H2O & Conc. Nitric Acid
• Treatment added to egg albumin: 5% TANNIC & PICRIC ACID

  give:

  • evidence of denaturation:
  • factor that causes denaturation:
  • ppt formation (TANNIC = light brown ppt), (PICRIC = yellow ppt)
  • alkaloidal
• Biuret Test

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:
  • peptide bonds
  • Biuret rgt: 10% NaOH 0.5% CuSO4
  • blue → pink / pale violet
  • Violet/purple (+)
  • Violet/purple (+)
• Ninhydrin

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:
  • amino group
  • 0.1% Ninhydrin soln
  • yellow → deep blue / violet color
  • Deep blue/ violet (+)
  • (slightly +)
• Xanthoproteic

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:
  • phenyl-containing amino acids
  • Conc HNO3 & NH4OH
  • yellow → orange
  • Orange color (+)
  • Yellow color (slightly +)
• Adamkiewickz

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:
  • tryptophan
  • Glacial acetic acid & Conc H2SO4
  • Violet ring
  • Violet ring (+)
  • (-) do not contain tryptophan
• Reduced Sulfur test

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:

  • cystine, cysteine, and methionine
  • 40% NaOH & Lead Acetate
  • black ppt
  • Brown-Black ppt of PbS
  • (-) do not contain cysteine
• Molisch Test

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:
  • carbohydrates
  • A-naphthol, 95% ethanol, & Conc. H2SO4
  • violet ring
  • Violet ring (+)
  • (-) do not contain carbohydrates
• Modified Neuman’s Test

  give:

  • test detected:
  • reagent:
  • color:
  • if albumin:
  • if gelatin:

  • Phosphate Moiety
  • 40% NaOH, Conc HNO3, & 0.2M (NH4)2MoO4
  • canary yellow ppt
  • Canary yellow ppt (+)
  • Canary yellow (+)