Solution to PS 7 #1
In the a-helix, H-bonds form between the
carbonyl oxygen of one residue and the a-amino
nitrogen 4 residues (one turn) away. The H-bonds are roughly parallel
to the axis of the a-helix. The amino
acid side chains point away from the backbone and do not particpate in
intrahelical bonding. In double stranded DNA the sugar phosphate
backbone is not involved in H-bonding. Instead, 2 or 3 H-bonds, which
are roughly perpendicular to the helix axis, form complementary bases on
opposite strands.
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