DNA의 응축을 유발시키는 spermine 농도 존재시 downward peak(trough)를 갖는 이례적 흡광도-온도 양상에 hydrophobic environment를 조성하는 DMSO의 영향을 조사하였다. DMSO 농도증가에 따라 downward peak의 깊이가 점차 얕아졌으며 그 phase transition enthalpy와 relative cooperative length(n)가 melting region보다는 downward peak(trough) phase transition에 더 예민하게 영향을 받았다. 따라서 본 data는 spermine에 의하여 유발되는 응축된 DNA 구조에 이르는 hydrophobic interaction에 의한 tertiary structure 형성이 온도상승에 따라 유리해짐으로써 downward peak가 생성된다는 추리를 확인하는 실험결과가 될 것이다.
In an effort to improve our knowledge on the mechanism of the collapse of DNA into a compact structure by polyamines, we investigated the effect of dimethyl sulfoxide (DMSO), a hydrophobic environmental reagent. on the anomalous absorbance-temperature profile of condensed DNA, induced by spermine and having a trough preceeded by the initiation of the melting phase. The trough peak size can be decreased by increased concentration of DMSO, and the cooperativity of the phase transition to the region in the anomalous absorbance-temperature profile is more sensitive to DMSO than that of the melting region of the profile. The present data indicate that the anomalous absorbance-temperature profile is due to the thermal stabilization of the tertiary structure of the spermine-induced collapsed state of DNA and the importance of hydrophobic interaction in the stabilization of the condensed state of DNA induced by spermine.
