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The structure of triple‐stranded G·2C polynucleotide helices
Author(s) -
Hattori Masao,
Frazier Joe,
Miles H. Todd
Publication year - 1976
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1976.360150309
Subject(s) - chemistry , polynucleotide , hydrogen bond , crystallography , thermal stability , stereochemistry , molecule , organic chemistry , biochemistry
The thermal stability of a new polynucleotide complex has been used to establish the hydrogen‐bonding structure of three‐stranded C‐G·CH + helices. In the Hoogsteen structure, the 8NH 2 group of 8NH 2 GMP can form a third hydrogen bond to the CH + strand, but in the alternative structure, the 8NH 2 group can form no interbase hydrogen bonds. For the new complex, 8NH 2 GMP·2 poly(C), a transition temperature of 80°C is observed under conditions in which the corresponding complex formed with 5′‐GMP has a T m of 20°C. We conclude from this 60° elevation of transition temperature that a third hydrogen bond is formed by the 8NH 2 group and that the structure must have Hoogsteen bonding. In order to be compatible with this structure in regular helices formed by U,C copolymers, A·2U bonding would also have to have a Hoogsteen structure.