Biochemistry 3381A Lecture Notes - Prokaryotic Small Ribosomal Subunit, Chromatin Remodeling, Helicase
12 Jan 2013
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Document Summary
20 angstroms is the width of the helix. Has a hole in the middle (no bases in the center of the helix) Z dna left handed and formed under high salt conditions. Salt helps mask the charges so the phosphates can be closer together. Chi angles are anti for py and syn for pu. Is real and it prevents the nucleosome core particles from forming. Many bonds along the backbone (alpha, beta) but due to steric clashes, restricts bonds from rotating freely. Py is always anti, pu can be either, if syn = z dna. Phosphate conformation bi = bases overlap, bii = bases more spaced out. 3 forces stabilizing nucleic acids: base stacking (vertical), base pairing (horizontal), ionic interaction. Base stacking result from van der waals and partial charge interactions. Gc base pairs have higher base stacking energy than at base pairs. Gc more stable, middle bond can"t be removed, anti-cooperativity. Divalent cations especially mg++ can stabilize ionic charges.
