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Published byBrianne White Modified over 9 years ago
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Biochemist’s View of the DNA Double Helix Major groove Minor groove
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Representative Nucleotides 5’ 3’ 2
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Chemist’s 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 1 H 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 We’ve 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 S N 2 reaction with stereospecificity
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