Thermodynamics of triple helix formation

Spectrophotometric studies on the d(A)10·2d(T)10 and d(C+3T3C+3)·d(G3A4G3)·d(C3T4C3) triple helices

Daniel Pilch, Roland Brousseau, Richard H. Shafer

Research output: Contribution to journalArticle

110 Citations (Scopus)

Abstract

We have stabilized the d(A)10·2d(T)10 and d(C+3T4C+3)·d(G3A4G3)·d(C3T4C3) triple helices with either NaCl or MgCl2 at pH 5.5. UV mixing curves demonstrate a 1:2 stoichtometry of purine to pyrimidine strands under the appropriate conditions of pH and ionic strength. Circular dichroic tltrations suggest a possible sequence-independent spectral signature for triplex formation. Thermal denaturation profiles indicate the initial loss of the third strand followed by dissociation of the underlying duplex with increasing temperature. Depending on the base sequence and ionic conditions, the binding affinity of the third strand for the duplex at 25°C is two to five orders of magnitude lower than that of the two strands forming the duplex. Thermodynamic parameters for triplex formation were determined for both sequences in the presence of 50 mM MgCl2 and/or 2.0 M NaCl. Hoogsteen base pairs are 0.22 - 0.64 kcal/mole less stable than Watson-Crick base pairs, depending on ionic conditions and base composition. C+·G and T·A Hoogsteen base pairs appear to have similar stability in the presence of Mg2+ ions at low pH.

Original languageEnglish (US)
Pages (from-to)5743-5750
Number of pages8
JournalNucleic acids research
Volume18
Issue number19
DOIs
StatePublished - Oct 11 1990

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Dilatation and Curettage
Thermodynamics
Base Pairing
Magnesium Chloride
Base Composition
Osmolar Concentration
Hot Temperature
Ions
Temperature
2'-deoxythymidylyl-(3'-5')-2'-deoxyadenosine

All Science Journal Classification (ASJC) codes

  • Genetics

Cite this

@article{930e371d4f18436db202124487cdf498,
title = "Thermodynamics of triple helix formation: Spectrophotometric studies on the d(A)10·2d(T)10 and d(C+3T3C+3)·d(G3A4G3)·d(C3T4C3) triple helices",
abstract = "We have stabilized the d(A)10·2d(T)10 and d(C+3T4C+3)·d(G3A4G3)·d(C3T4C3) triple helices with either NaCl or MgCl2 at pH 5.5. UV mixing curves demonstrate a 1:2 stoichtometry of purine to pyrimidine strands under the appropriate conditions of pH and ionic strength. Circular dichroic tltrations suggest a possible sequence-independent spectral signature for triplex formation. Thermal denaturation profiles indicate the initial loss of the third strand followed by dissociation of the underlying duplex with increasing temperature. Depending on the base sequence and ionic conditions, the binding affinity of the third strand for the duplex at 25°C is two to five orders of magnitude lower than that of the two strands forming the duplex. Thermodynamic parameters for triplex formation were determined for both sequences in the presence of 50 mM MgCl2 and/or 2.0 M NaCl. Hoogsteen base pairs are 0.22 - 0.64 kcal/mole less stable than Watson-Crick base pairs, depending on ionic conditions and base composition. C+·G and T·A Hoogsteen base pairs appear to have similar stability in the presence of Mg2+ ions at low pH.",
author = "Daniel Pilch and Roland Brousseau and Shafer, {Richard H.}",
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Thermodynamics of triple helix formation : Spectrophotometric studies on the d(A)10·2d(T)10 and d(C+3T3C+3)·d(G3A4G3)·d(C3T4C3) triple helices. / Pilch, Daniel; Brousseau, Roland; Shafer, Richard H.

In: Nucleic acids research, Vol. 18, No. 19, 11.10.1990, p. 5743-5750.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Thermodynamics of triple helix formation

T2 - Spectrophotometric studies on the d(A)10·2d(T)10 and d(C+3T3C+3)·d(G3A4G3)·d(C3T4C3) triple helices

AU - Pilch, Daniel

AU - Brousseau, Roland

AU - Shafer, Richard H.

PY - 1990/10/11

Y1 - 1990/10/11

N2 - We have stabilized the d(A)10·2d(T)10 and d(C+3T4C+3)·d(G3A4G3)·d(C3T4C3) triple helices with either NaCl or MgCl2 at pH 5.5. UV mixing curves demonstrate a 1:2 stoichtometry of purine to pyrimidine strands under the appropriate conditions of pH and ionic strength. Circular dichroic tltrations suggest a possible sequence-independent spectral signature for triplex formation. Thermal denaturation profiles indicate the initial loss of the third strand followed by dissociation of the underlying duplex with increasing temperature. Depending on the base sequence and ionic conditions, the binding affinity of the third strand for the duplex at 25°C is two to five orders of magnitude lower than that of the two strands forming the duplex. Thermodynamic parameters for triplex formation were determined for both sequences in the presence of 50 mM MgCl2 and/or 2.0 M NaCl. Hoogsteen base pairs are 0.22 - 0.64 kcal/mole less stable than Watson-Crick base pairs, depending on ionic conditions and base composition. C+·G and T·A Hoogsteen base pairs appear to have similar stability in the presence of Mg2+ ions at low pH.

AB - We have stabilized the d(A)10·2d(T)10 and d(C+3T4C+3)·d(G3A4G3)·d(C3T4C3) triple helices with either NaCl or MgCl2 at pH 5.5. UV mixing curves demonstrate a 1:2 stoichtometry of purine to pyrimidine strands under the appropriate conditions of pH and ionic strength. Circular dichroic tltrations suggest a possible sequence-independent spectral signature for triplex formation. Thermal denaturation profiles indicate the initial loss of the third strand followed by dissociation of the underlying duplex with increasing temperature. Depending on the base sequence and ionic conditions, the binding affinity of the third strand for the duplex at 25°C is two to five orders of magnitude lower than that of the two strands forming the duplex. Thermodynamic parameters for triplex formation were determined for both sequences in the presence of 50 mM MgCl2 and/or 2.0 M NaCl. Hoogsteen base pairs are 0.22 - 0.64 kcal/mole less stable than Watson-Crick base pairs, depending on ionic conditions and base composition. C+·G and T·A Hoogsteen base pairs appear to have similar stability in the presence of Mg2+ ions at low pH.

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