Natural Product Biomolecules - Organic Chemistry Concepts: An EFL Approach - page 168

Q 8.6. Hydrolysis of an optically active triglyceride gives one equivalent
each of glycerol and oleic acid along with two equivalents of stearic
acid. Draw a possible structural formula for the triglyceride.
Q 8.7. How many moles of hydrogen would be consumed during the
hydrogenation of an oil which has one unit each of oleic,
linoleic, and linolenic acids? Draw a structural representation of
the product.
Q 8.8. Draw the general fused hydrocarbon ring system which is character-
istic of a steroid. Explain why steroids are classified as lipids,
although they do not have any fatty acid component.
Q 8.9. Draw the zwitterions, conjugate acids, and conjugate bases for the
amino acids alanine and serine.
PROGRAM 26 Amino Acid Isoelectric Points
A The isoelectric point (pI) is a physical property of each amino acid. At the isoelectric
point, the solubility of the amino acid is minimized. This is because, at the isoelectric
point pH, the concentration of the zwitterion is at a maximum. This can be shown by a
study of the species that is formed from an amino acid as the pH changes.
In the alanine example above, the zwitterion species dominates when the solution is
between the pH values of 2.3 and 9.9.
Comment on the species present at each of the pH extremes.