Force-induced melting of DNA hairpin: Unfolding pathways and phase diagrams.

Using the exact enumeration technique, we have studied the force-induced melting of a DNA hairpin on the face centered cubic lattice for two different sequences which differ in terms of loop closing base pairs. The melting profiles obtained from the exact enumeration technique is consistent with the Gaussian network model and Langevin dynamics simulations. Probability distribution analysis based on the exact density of states revealed the microscopic details of the opening of the hairpin.

Compliance Assessment of Tobacco Products to Cigarettes and Other Tobacco Products Act in India with Reference to Third Amendment Rules, 2020.

Objective: Tobacco use is associated with mortality in low- and middle-income countries including India with dual burden of smoking and smokeless tobacco (SLT). Aligning with the FCTC, India has made substantial amendments in strengthening graphic warning under Cigarettes and Other Tobacco Products Act (COTPA) for sections 7,8 9 and "Specified warning". Compliance assessment studies are necessary to understand current status of implementation for packaging laws.

Can one detect intermediate denaturation states of DNA sequences by following the equilibrium open-close dynamic fluctuations of a single base pair?

Melting of DNA sequences may occur through a few major intermediate states, whose influence on the melting curve has been discussed previously, while their effect on the kinetics has not been explored thoroughly. Here, we chose a simple DNA sequence, forming a hairpin in its native (zipped) state, and study it using molecular dynamic (MD) simulations and a model integrating the Gaussian network model with bond-binding energies-the Gaussian binding energy (GBE) model. We find two major partial denaturation states, a bubble state and a partial unzipping state.

Manipulation of double-stranded DNA melting by force.

By integrating elasticity-as described by the Gaussian network model-with bond binding energies that distinguish between different base-pair identities and stacking configurations, we study the force induced melting of a double-stranded DNA (dsDNA). Our approach is a generalization of our previous study of thermal dsDNA denaturation [J. Chem.

Sufficient minimal model for DNA denaturation: Integration of harmonic scalar elasticity and bond energies.

We study DNA denaturation by integrating elasticity - as described by the Gaussian network model - with bond binding energies, distinguishing between different base pairs and stacking energies. We use exact calculation, within the model, of the Helmholtz free-energy of any partial denaturation state, which implies that the entropy of all formed "bubbles" ("loops") is accounted for. Considering base pair bond removal single events, the bond designated for opening is chosen by minimizing the free-energy difference for the process, over all remaining base pair bonds.

Force induced melting of the constrained DNA.

We develop a simple model to study the effects of the applied force on the melting of a double stranded DNA (dsDNA). Using this model, we could study the stretching, unzipping, rupture and slippagelike transition in a dsDNA. We show that in absence of an applied force, the melting temperature and the melting profile of dsDNA strongly depend on the constrained imposed on the ends of dsDNA.

Force induced unfolding of biopolymers in a cellular environment: a model study.

Effect of molecular crowding and confinement experienced by protein in the cell during unfolding has been studied by modeling a linear polymer chain on a percolation cluster. It is known that internal structure of the cell changes in time, however, they do not change significantly from their initial structure. In order to model this we introduce the correlation among the different disorder realizations.

Effects of molecular crowding on stretching of polymers in poor solvent.

We consider a linear polymer chain in a disordered environment modeled by percolation clusters on a square lattice. The disordered environment is meant to roughly represent molecular crowding as seen in cells. The model may be viewed as the simplest representation of biopolymers in a cell.