• R Malathi

      Articles written in Journal of Biosciences

    • Chain flexibility and configurational dimensions of left handed Z- DNA and right handed B-DNA helices

      R Malathi N Yathindra

      More Details Abstract Fulltext PDF

      The configurational behaviour of flexible helices of right handed B- and left handed Z-types have been analysed using statistical mechanical procedures. The configuration-dependent parameter, most importantly, the persistence length has been computed, using the heminucleotide scheme of treating polynucleotide chains under the approximation that perturbations in the backbone torsions produce sufficient flexibility in these helices. The values of persistence lengths obtained for Z-helices are very much higher than that of B-helices indicating that former is less flexible compared to the latter. These are in accordance with the results obtained recently on B- and Z-forms of poly(dG-dC). (dG-dC) using light scattering studies. Also the persistence lengths of BII-DNA helices characterised by a skew 3'-hemiucleotide (ε-270°), and also when they coexist with B-DNA have been computed and the values lie within the range of experimentally reported values on B-helices. It is argued that the decrease in the persistence length values of B-DNA at higher salt concentration is due to additional small fluctuations in sugar residue torsions induced due to neutralisation of electrostatic repulsions between adjacent phosphates of the nucleotide. Noteworthy is that these are correlated to winding angle variations and the consequent bending of the helix.

    • Non-Watson Crick base pairs might stabilize RNA structural motifs in ribozymes — a comparative study of group-I intron structures

      K Chandrasekhar R Malathi

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      In recent decades studies on RNA structure and function have gained significance due to discoveries on diversified functions of RNA. A common element for RNA secondary structure formed by series of non-Watson/Watson Crick base pairs, internal loops and pseudoknots have been the highlighting feature of recent structural determination of RNAs. The recent crystal structure of group-I introns has demonstrated that these might constitute RNA structural motifs in ribozymes, playing a crucial role in their enzymatic activity. To understand the functional significance of these non-canonical base pairs in catalytic RNA, we analysed the sequences of group-I introns from nuclear genes. The results suggest that they might form the building blocks of folded RNA motifs which are crucial to the catalytic activity of the ribozyme. The conservation of these, as observed from divergent organisms, argues for the presence of non-canonical base pairs as an important requisite for the structure and enzymatic property of ribozymes by enabling them to carry out functions such as replication, polymerase activity etc. in primordial conditions in the absence of proteins.

  • Journal of Biosciences | News

      Forthcoming Special issue.

    • To trigger further research on plant mitochondria, the Journal of Biosciences is bringing out a special issue titled "Plant Mitochondria: Properties and Interactions with Other Organelles".

      Plant mitochondria are quite distinct and have unique features, such as a cyanide-insensitive alternate pathway. They also interact with chloroplasts to optimize photosynthetic carbon assimilation.

      Submissions are welcome until 30 July 2023. The contributions can be original articles, short communications, reviews, or mini-reviews on any topic related to plant mitochondria.

      Authors can submit their articles online at https://www.editorialmanager.com/jbsc/default2.aspx

      Posted on April 12, 2023
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      Posted on July 25, 2019

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