Raman Spectra of Single Crystals of r(GCG)d(CGC) and d(CCCCGGGG) as Models for A DNA, Their Structure Transitions in Aqueous Solution, and Comparison with Double-Helical Poly(dG)•Poly(dC)

A. H.J. Wang, A. Rich, Y. Kyogoku, J. M. Benevides, G. J. Thomas, G. A. Van Der Marel, J. H. Van Boom

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101 引文 斯高帕斯(Scopus)

摘要

The self-complementary oligonucleotides [r(CGC)d(CGC)]2 and [d(CCCCGGGG)]2 in single-crystal and solution forms have been investigated by Raman spectroscopy. Comparison of the Raman spectra with results of single-crystal X-ray diffraction and with data from polynucleotides permits the identification of a number of Raman frequencies diagnostic of the A-helix structure for GC sequences. The guanine ring frequency characteristic of C3'-endo pucker and anti base orientation is assigned at 668 ± 2 cm−1 for both dG and rG residues of the DNA/RNA hybrid [r(GCG)d(CGC)]2. The A-helix backbone of crystalline [r(GCG)d(CGC)]2 is altered slightly in the aqueous structure, consistent with the conversion of at least two residues to the C2'-endo/anti conformation. For crystalline [d(CCCCGGGG)]2, the Raman and X-ray data indicate nucleosides of alternating 2'-endo-3'-endo pucker sandwiched between terminal and penultimate pairs of C3'-endo pucker. The A-A-B-A-B-A-A-A backbone of the crystalline octamer is converted completely to a B-DNA fragment in aqueous solution with Raman markers characteristic of C2'-endo/anti-G (682 ± 2) and the B backbone (826 ± 2 cm−1). In the case of poly(dG)•poly(dC), considerable structural variability is detected. A 4% solution of the duplex is largely A DNA, but a 2% solution is predominately B DNA. On the other hand, an oriented fiber drawn at 75% relative humidity reveals Raman markers characteristic of both A DNA and a modified B DNA, not unlike the [d-(CCCCGGGG)]2 crystal. A comparison of Raman and CD spectra of the aqueous [d(CCCCGGGG)]2 and poly(dG)•poly(dC) structures suggests the need for caution in the interpretation of CD data from G clusters in DNA.

原文英語
頁(從 - 到)41-50
頁數10
期刊Biochemistry
25
發行號1
DOIs
出版狀態已發佈 - 1月 1 1986
對外發佈

ASJC Scopus subject areas

  • 生物化學

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