The thermal denaturation of the native DNA in solvents of varying salt concentrations was studied by viscometric and spectrophotometric methods. It was observed that within the molarity range of 0.02 M to 0.3 M, the melting temperatures obtained by the two independent methods agreed well, but that at lower ionic strength the agreement was not satisfactory. Both the viscometric and the spectrophotometric measurements showed an increase of the melting temperature with increasing counterion concentration and a levelling off effect in the neighbourhood of 0.3 M. © 1974, Walter de Gruyter. All rights reserved.

CHANDRA D GOKUL

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University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Zeitschrift fur Naturforschung - Section C Journal of Biosciences

The binding of proflavine to native DNA increased its stability against thermal denaturation as measured by viscometric method. Up to a moderate ionic strength of 0.058 M, the melting temperature of the complex increased almost linearly with the increase of dye concentrations and a saturation was reached when one proflavine molecule was added per four to five DNA-Phosphates (DIP ≅ 0.2). The extent of stabilization (ΔTm) produced by dye binding decreased gradually with the increase of ionic strength and no stabilization effect was observed at an ionic strength of about 0.3 M. The maximum melting temperature attained by Proflavine binding was almost in dependent of the ionic strength of the medium. The same maximum value was reached as obtained simply by increasing the sodium ion concentration. © 1974, Walter de Gruyter. All rights reserved.

Viscometric Studies on the Stability of DNA-Proflavine Complex-II

Escherichia coli DNA was denatured by heating in two solvents at different temperatures and subsequently renatured by annealing. Ultraviolet absorption and sedimentation techniques were used to characterise the physical state of the irreversibly denatured and of the annealed DNA. Simultaneous electron microscopic studies were carried out in order to obtain more direct and quantitative information. Definite evidence has been presented for the separation of the twin strands, their degradation and random coiling when heated to about Tm+15°. Annealed DNA in the high molarity solvent had native-like regions with flower-like unmatched single strands, mostly at the ends. The effect of annealing was less in the low molarity solvent. The molecular weights of the denatured and the renatured DNA were obtained from electron microscopic length measurements and compared with those derived from S-M relationships. © 1969.

Journal	Zeitschrift fur Naturforschung - Section C Journal of Biosciences
Publisher	-
ISSN	0939-5075