A new probe for the indirect measurement of the conformation and interaction of biopolymers at extremely high temperatures using a capillary flow hydrothermal reactor system for UV-vis spectrophotometry

The scope of the capillary flow hydrothermal reactor system for the UV-vis spectrophotometric detection (CHUS), which was recently developed in our group for the in situ UV-vis monitoring of hydrothermal reactions at the millisecond-second time range, has been investigated as a potential new probe for the analysis of conformations and interactions of polynucleotides at extremely high temperatures. It was possible to detect indirectly the difference between double-stranded and single-stranded DNA on the basis of the intercalation with ethidium bromide (EB). Measurements of absorbance of the DNA-EB complex were attempted at up to 200 °C by the CHUS system, and the results were consistent with the melting behavior observed by differential scanning calorimetry. This fact indicates that the CHUS system enables a rapid monitoring where the decomposition of both DNA and the intercalator did not interfere with the measurements. Since these results elucidate that the CHUS system can readily be applied for monitoring UV-vis absorbance at 100-300 °C, this study supports that the CHUS method is applicable as a new probe for exploring interactions and conformation within polynucleotides at high temperatures, such as in hyperthermophilus.