The synthesis of deoxynucleotide kinase (EC 2.7.4.2) in vitro by a preparation consisting of T4 bacteriophage DNA and a cell-free extract of Escherichia coli has been reported. A study of the role of monovalent cations in the synthesis of this enzyme as well as alpha-glucosyl transferase (EC 2.4.1.2) shows that potassium ions are required for maximal enzyme production. Examination of the RNA-di...

for an Invited Paper for the MAR08 Meeting of The American Physical Society Ionand pH-dependent volume transitions in biopolymer gels FERENCE HORKAY, Laboratory of Integrative and Medical Biophysics, National Institutes of Health Swelling and collapse of polyelectrolyte gels are the result of a balance of different interactions that control the osmotic pressure and network elasticity. In biopol...

We used whole-cell recording to characterize ion permeation, rectification, and block of monovalent current through calcium release-activated calcium (CRAC) channels in Jurkat T lymphocytes. Under physiological conditions, CRAC channels exhibit a high degree of selectivity for Ca2+, but can be induced to carry a slowly declining Na+ current when external divalent ions are reduced to micromolar ...

The iron storage protein ferritin contains threefold and fourfold symmetric channels that are thought to provide pathways for the transfer of Fe(2+) ions in and out of the protein. Using the known crystal structure of the ferritin protein, we perform electrostatic potential energy calculations to elucidate the functional properties of these channels. The threefold channel is shown to be respons...

In contrast to folded proteins, intrinsically disordered proteins (IDPs) lack a stable three-dimensional structure but, nevertheless, are involved in many biological processes and have a crucial role in various human diseases, including degenerative neuropathies, amyloidosis, and cancer. I will show how advanced single-molecule spectroscopy in combination with Förster resonance energy transfer ...

We use coarse-grained Monte Carlo simulations to study the elastic properties of charged membranes in solutions of monovalent and pentavalent counterions. The simulation results of the two cases reveal trends opposite to each other. The bending rigidity and projected area increase with the membrane charge density for monovalent counterions, while they decrease for the pentavalent ions. These ob...

Alkali (Li(+), Na(+), K(+), Rb(+), and Cs(+)) and halide (F(-), Cl(-), Br(-), and I(-)) ions play an important role in many biological phenomena, roles that range from stabilization of biomolecular structure, to influence on biomolecular dynamics, to key physiological influence on homeostasis and signaling. To properly model ionic interaction and stability in atomistic simulations of biomolecul...