Shinoo Srivastava

STABILITY AND TRANSITION IN A DNA TETRAPLEX: A MODEL FOR TELOMERES

The theory of cooperative transition has been applied to explain the stability and melting behavior in a DNA tetraplex, which is a model for telomeres. The transition profile and heat capacity curves are best explained in terms of two variable parameters, namely nucleation and propagation parameters. The effect of strand concentration and consequent change in enthalpy is reflected in the sharpness of transition and change in nucleation parameter. The same is true for greater stabilization in the presence of K+ ions, compared with the Na+ ion. It is ascribed to dipole and dipole-induced interactions.

Phonon Dispersion in Polypyrrole

A study of the normal modes of vibration and their dispersion in polypyrrole (PPY) based on the Urey-Bradley force field is reported. It gives a fuller interpretation of previously reported FTIR spectra. Characterstic features of dispersion curves, such as regions of high density-of-states, repulsion, and character mixing of dispersive modes, are discussed. Predictive values of heat capacity as a function of temperature are reported.

Phonon dispersion in polyguanylic acid

Abstract A study of the normal modes of vibration and their dispersion in polyguanylic acid along the chain axis (tetrad form) based on Urey–Bradley force field and Raman and Fourier transform infrared is reported. It has been greatly assisted by the vibrational analysis of guanine tetrad and spectral information for telomeric DNA d(G 12 ). Spectral relationship for polyG, telomeric DNA d(G 12 ) and characteristic features of dispersion curves such as regions of high density-of-states, repulsion and character mixing are discussed. Predictive value of heat capacity as a function of temperature is reported.

Vibrational Dynamics of l‐Proline‐l‐Hydroxyproline: A Fragment of Collagen

Normal mode studies are reported for l‐proline l‐hdroxyproline, a fragment of collagen. A comparision of amide I mode in peptide with that in collagen shows the presence of such sequences in collagen. Other possible sequences show appreciable differences, and hence they are not likely to be present in large numbers.

Impact of cis/trans‐Platin Binding on DNA Stability

Abstract Both cis‐ and trans‐platins are known to form intra‐ and interstrand cross‐linking with DNA. The nature and strength of binding is different, which makes their efficacy as antitumor drugs different. Zimm and Bragg theory has been amended to explain the melting behavior and heat capacity of DNA with and without platin binding.

Phonon dispersion in polyadenylic acid

A study of the normal modes of vibration and their dispersion in polyadenylic acid based on the Urey–Bradley force field is reported. It gives a better interpretation of FTIR spectra as compared with the valence force field. Characteristic features of dispersion curves such as regions of high density‐of‐states, repulsion, and character mixing of dispersive modes are discussed. Predictive valuzes of heat capacity as a function of temperature are reported.