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Title: Analysis of the possible helical structures of nucleic acids and polynucleotides. Application of (n-h) plots. Author: Yathindra N, Sundaralingam M. Journal: Nucleic Acids Res; 1976 Mar; 3(3):729-47. PubMed ID: 1272796. Abstract: The two helical parameters n and h where n is the number of nucleotide residues per turn and h is the height per nucleotide residue have been evaluated for single stranded helical polynucleotide chains comprising C(3') -endo and C(2') endo class of nucleotides. The helical parameters are found to be especially sensitive to the C(4')-C(3') (sugar pucker) and the C(4')-C(5') torsions. The (n-h) plots display only one important helix forming domain for each class of nucleotides characterized by the sugar pucker and the C(4')-C(5') torsion. A correlation between the (n-h) plots and the known RNA (A,A') and DNA (A,B,C) helical forms has been established. It is found that all forms of helices except the C-DNA possess a favorable combination of P-O torsions. The analysis of the (n-h) plots suggests that C-DNA can have a conformation very similar to B-DNA. Although the (n-h) plots predict the stereochemical possibility of both right-handed and left-handed helices, nucleic acids apparently prefer right-handed conformation because of the energetics associated with the sugar-phosphate backbone and the base.[Abstract] [Full Text] [Related] [New Search]