Exam W in class

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Exam W in class BRING YOUR CALCULATOR! Review
Sessions M 4 and T 12 SL 140
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Isoelectric Point pI
pI pH at which a molecule has 0 net charge
For amino acids with no ionizable R groups, pI
pK1 pK2 2
For all others, you must determine which 2 pKs
determine the pI by inspection.
What is the pI for asp?
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Other Properties of Amino Acids

• Stereochemistry (all biosynthetic proteins made
  up of L-isomer)
• Hydropathy (partitioning between polar and
  nonpolar solvents as indicator of polarity)
• these two properties are major determinants of
  peptide conformation

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Figure 4-7 Titration curves of the enzyme
ribonuclease A at 25C.
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Bloody Fact

• If 1 mL of 10 N HCl is added to 1 liter of saline
  solution at pH 7.0, the pH will decrease to
  roughly pH 2.
• If 1 mL of 10 N HCl is added to 1 liter of blood
  plasma at pH 7.4, the pH will decrease to pH
  7.2.
• Why? Blood is buffered (in this case by the
  H2CO3/HCO3 system).

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Figure 4-3 Condensation of two a-amino acids to
form a dipeptide.
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Figure 4-8 The tetrapeptide Ala-Tyr-Asp-Gly.
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Stryer Fig.3.19
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Stryer Fig.3.20
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Glutathione
?-E-C-G
2 Glut-SH
Glut-S-S-Glut 2H 2e-
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Chapter 5 Nucleic Acids
Skim over this chapter on your own.
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Bioinformatics Chapter 7 Special lecture by Dr.
Jeff Young on Friday.
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Yipee!!! Protein Structure!!!
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Figure 7-1 The structural hierarchy in proteins.
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Figure 8-1 The trans-peptide group.
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Figure 8-2 The cis-peptide group.
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Figure 8-3 A polypeptide chain in its fully
extended conformation showing the planarity of
each of its peptide groups.
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Figure 8-6 Steric interference between adjacent
residues.
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Figure 8-7 The Ramachandran diagram.
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Figure 8-4 The torsional degrees of freedom in a
peptide unit.
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Figure 8-8 Conformation angles in proteins.
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Figure 8-9 The Ramachandran diagram of Gly
residues in a polypeptide chain.
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