Raman spectroscopic measurements in self-pressurized aqueous solutions above 100°C: The melting of poly(G) and poly(G) · poly(C)

• Published in: Biopolymers Vol. 49; no. 1; pp. 21 - 28
• Main Authors: Mercier, Pascal, Carrier, Virginie, Roy, Simon, Savoie, Rodrigue
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.01.1999
• Subjects: aqueous solution; melting; polyguanylic acid; polyguanylic-polycytidylic acid; Raman spectra; self-association
• ISSN: 0006-3525; 1097-0282
• DOI: 10.1002/(SICI)1097-0282(199901)49:1<21::AID-BIP3>3.0.CO;2-Y

We have studied by Raman spectroscopy the thermal behavior of associated polyguanylic acid [poly(G)] and polyguanylic–polycytidylic acid [poly(G) · poly(C)] in self‐pressurized aqueous solutions contained in sealed capillary tubes. The associated polynucleotides were found to be very resistant to heat, but evidence of thermal degradation was observed after melting of the helical structures. The cooperative melting transition of the four‐stranded complex of poly(G) was located at 141°C in 0.5M KCl, 135°C in 0.5M NaCl, 129°C in 0.5M LiCl, 123°C in 0.1M tetramethylammonium perchlorate, and 105°C in 0.1M tetraethylammonium bromide solutions. The transition was observed at 130°C in poly(G) · poly(C) (in 0.5M NaCl). The results in this case show that a four‐stranded poly(G) complex is formed following the melting of the double helix. © 1999 John Wiley & Sons, Inc. Biopoly 49: 21–28, 1999