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Methylation and demethylation of DNA, RNA and proteins has emerged as a major regulatory mechanism. Studying the function of these modifications would benefit from tools for their site-specific inhibition and timed removal. S-Adenosyl-L-methionine (AdoMet) analogs in combination with methyltransferases (MTases) have proven useful to map or block and release MTase target sites, however their enzymatic generation has been limited to aliphatic groups at the sulfur atom. We engineered a SAM synthetase from Cryptosporidium hominis (PC-ChMAT) for efficient generation of AdoMet analogs with photocaging groups that are not accepted by any WT MAT reported to date. The crystal structure of PC-ChMAT at 1.87 revealed how the photocaged AdoMet analog is accommodated and guided engineering of a thermostable MAT from Methanocaldococcus jannaschii. PC-MATs were compatible with DNA-and RNA-MTases, enabling sequence-specific modification ("writing") of plasmid DNA and light-triggered removal ("erasing").

The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with an assumption of incomplete self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring three competing configurations: in-plane and out-of-plane ferromagnetism and vortex formation. The influence of the vortex core on the scaling behavior and phase diagram is analyzed. Threedimensional phase diagrams are obtained for cylindrical nanorings, depending on their height, outer and inner radius. The triple points in these phase diagrams are shown to be in linear relationship with the inner radius of the ring. Elliptically shaped magnetic nanoparticles are also studied. A new parametrization for double vortex configurations is proposed, and regions in the phase diagram are identified where the double vortex is a stable ground state.

We study the domain ordering kinetics in d = 2 ferromagnets which corresponds to populated neuron activities with both long-ranged interactions, V(r) ∼ r −n and short-ranged interactions. We present the results from comprehensive Monte Carlo (MC) simulations for the nonconserved Ising model with n ≥ 2, interaction range considering near and far neighbors. Our model results could represent the long-ranged neuron kinetics (n ≤ 4) in consistent with the same dynamical behaviour of short-ranged case (n ≥ 4) at far below and near criticality. We found that emergence of fast and slow kinetics of long and short ranged case could imitate the formation of connections among near and distant neurons. The calculated characteristic length scale in long-ranged interaction is found to be n independent (L(t) ∼ t 1/(n−2)), whereas short-ranged interaction follows L(t) ∼ t 1/2 law and approximately preserve universality in domain kinetics. Further, we did the comparative study of phase ordering near the critical temperature which follows different behaviours of domain ordering near and far critical temperature but follows universal scaling law.

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