Polymers of life

Question 1

test-tube experiments
involving amino acids

Answer 1

• Resist change in pH when small amount of strong acid or base added (buffer
  solutions)
• No reaction with ethanoyl chloride (no free amine group. Compare to reaction of
  amines with ethanoyl chloride to make amides)
• No effervescence with carbonate (carboxylic acid is already ionised)

Question 2

experiments involving the hydrolysis of
peptides

Answer 2

Experiment (e.g. hydrolysis of aspartame)

Technique:
* Crush solid to a powder
* Add to round bottom flask, with some anti-bumping granules (to break up large
bubbles)
* Heat under reflux with moderately concentrated hydrochloric acid
* Use TLC or paper chromatography to identify the amino acids present

visualise using ninhydrin (only ninhydrin for amino acids).

Question 3

Analysis:

Answer 3

• If hydrolysis was successful – there should be several spots above the place the
  hydrolysed mixture was spotted onto the paper.
• The heights of spots should match the heights of the spots for the pure amino acids
• No need to work out Rf values unless you have any unidentified spots