Welcome to 3FF3! Bio-organic Chemistry

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Biochemists View of the DNA Double Helix
Minor groove
Major groove
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Representative Nucleotides
2
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3
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Chemists View
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Contrast with Nucleic Acid Bases (A, T, C, G, U)
Specific!

• Evidence for specificity?
• Why are these interactions specific? e.g. G-C
  A-T

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• Evidence?
• If mix G C together ? exothermic reaction
  occurs change in 1H chemical shift in NMR other
  changes ? reaction occurring
• Also occurs with A T
• Other combinations ? no change!

e.g. Guanine-Cytosine

• Why?
• In G-C duplex, 3 complementary H-bonds can form
  donors acceptors molecular recognition

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Mechanism?
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Properties of Pyridine

• Weve seen it as an acid an H-bond acceptor
• Lone pair can act as a nucleophile

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Another example of N-Alkylation of Pyridines
This is an SN2 reaction with stereospecificity