Biophysical Reviews and Letters

(Ionic liquids) ILs have unique properties compared with conventional solvents, opening a wide range of application as solvents and catalysts. ILs' cytotoxicity extend their application in biomedicine by acting as antimicrobial and anticancer agents. This article reviews the current research advances of ILs' biomedical application from the following four aspects: solvents, catalysts, antimicrobial and anticancer agents. By introducing ILs' interesting structures and their corresponding unique properties, this review concludes the current state-of-art of ILs biomedical applications. We also try to point out the ILs issues and solutions for more potential applications in biomedicine.

DNA, RNA and proteins are among the most important macromolecules in a living cell. These molecules are polymerized by molecular machines. These natural nano-machines polymerize such macromolecules, adding one monomer at a time, using another linear polymer as the corresponding template. The machine utilizes input chemical energy to move along the template which also serves as a track for the movements of the machine. In the Alan Turing year 2012, it is worth pointing out that these machines are "tape-copying Turing machines". We review the operational mechanisms of the polymerizer machines and their collective behavior from the perspective of statistical physics, emphasizing their common features in spite of the crucial differences in their biological functions. We also draw the attention of the physics community to another class of modular machines that carry out a different type of template-directed polymerization. We hope this review will inspire new kinetic models for these modular machines.

First, we briefly describe the general growth mechanism, which governs the growth of living organisms, and its mathematical representation, the growth equation. Using the growth equation, we compute the growth curve for S. cerevisiae and show that it corresponds to available experimental data. Then, we propose a new method for finding the amount of synthesized biomass without complicated stoichiometric computations and apply this method to evaluation of biomass production by S. cerevisiae. We find that obtained results are very close to values obtained by methods of metabolic flux analysis. Since methods of metabolic flux analysis require finding produced biomass, which is one of the most important parameters affecting stoichiometric models, a priori knowledge of produced biomass can significantly improve methods of metabolic flux analysis in many aspects, which we also discuss. Besides, based on the general growth mechanism, we considered evolutionary development of S. cerevisiae and find that it is a more ancient organism than S. pombe and is apparently its direct predecessor.

Protein tyrosine phosphorylation is a post-translational modification mechanism, crucial for the regulation of nearly all aspects of cell life. This dynamic, reversible process is regulated by the balanced opposing activity of protein tyrosine kinases and protein tyrosine phosphatases. In particular, the protein tyrosine phosphatase 1B (PTP1B) is implicated in the regulation of the insulin-receptor activity, leptin-stimulated signal transduction pathways and other clinically relevant metabolic routes, and it has been found overexpressed or overregulated in human breasts, colon and ovary cancers. The WPD loop of the enzyme presents an inherent flexibility, and it plays a fundamental role in the enzymatic catalysis, turning it into a potential target in the design of new efficient PTP1B inhibitors. In order to determine the interactions that control the spatial conformation adopted by the WPD loop, complexes between the enzyme and halide ions (Br^- and I^- in particular) were crystallized and their crystallographic structure determined, and the collective movements of the aforementioned complexes were studied through Molecular Dynamics (MD) simulations. Both studies yielded concordant results, indicating the existence of a relationship between the identity of the ion present in the complex and the strength of the interactions it establishes with the surrounding protein residues.

This paper reports an in vivo characterization technique to characterize dielectric properties of living tissues and bio-molecules at microwave frequency using cavity perturbation technique, where a slot ring resonant sensor has been used, that works at 8 GHz and has been designed to enumerate the effective dielectric constant of Spirulina platensis and chlorophyll molecule. Observed value of the dielectric constant of Spirulina platensis was 8 ± 0.04 in the absence of light and 14.575 ± 0.145 in the presence of light. Molecular polarizability of chl a molecule was 5.07 ± 0.05 × 10⁴ ų. Experimentally calculated local electric field actually experienced by chl a molecule was 14.197 ± 0.003 V/m for applied field of 9.79 V/m across the slot ring, dipole moment of chl a molecule was 2.175 ± 0.005 × 10⁵ Debye and total polarisation produced due to these molecules was 1.545 ± 0.005 C/m². Observed relaxation time of chl a molecule was 8.09 ± 0.18 × 10^-9s. The proposed sensing method can be an alternate to spectral characterisation technique, generally used to characterize light sensitive bio-molecules and can also be extended to characterize light sensitive bio-molecules in plant cells.