Effect of a modified thymine on the structure and stability of [d(TGGGT)]4 quadruplex.
Telomeric guanine-rich sequence can adopt quadruplex structures that are important for their biological role in chromosomal stabilisation. G quartets are characterised by the cyclic hydrogen bonding of four guanine bases in a coplanar arrangement and their stability is ion-dependent. In this work we compare the stability of [d(TGGGT)](4) and [d(T*GGGT)](4) quadruplexes. The last one contains a modified thymine, where the hydroxyl group substitutes one hydrogen atom of the methyl group of the thymine in the [d(TGGGT)](4) sequence. We used a combination of spectroscopic, calorimetric and computational techniques to characterise the G-quadruplex formation. NMR and CD spectra of [d(T*GGGT)](4) were characteristic of parallel-stranded, tetramolecular quadruplex. CD and DSC melting experiments reveal that [d(T*GGGT)](4) is less stable that unmodified quadruplex. Molecular models suggest possible explanation for the observed behaviour.
Petraccone
Luigi
L
Dipartimento di Chimica, Via Cintia, Università Federico II di Napoli, Monte Sant' Angelo, 80126 Naples, Italy.
Erra
Eva
E
Nasti
Lucia
L
Galeone
Aldo
A
Randazzo
Antonio
A
Mayol
Luciano
L
Barone
Guido
G
Giancola
Concetta
C
D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D013696:Temperature; D013941:Thymine / Q000737:chemistry*; D013997:Time Factors
D006147:Guanine; D004247:DNA; D013941:Thymine