Environment- and Conformation-Induced Frequency Shifts of C-D Vibrational Stark Probes in NAD(P)H Cofactors.

NAD(P)H cofactors are found in all forms of life and are essential for electron and hydrogen atom transfer. The linear response of a carbon-deuterium (C-D) vibration based on the vibrational Stark effect can facilitate measurements of electric fields for critical biological reactions including cofactor-mediated hydride transfer. We find both inter- and intramolecular electric fields influence the C-D frequency in NAD(P)H and nicotinamide-like models where the reactive C4-hydrogen has been deuterated.

Structure-function relationships in pure archaeal bipolar tetraether lipids.

Archaeal bipolar tetraether lipids (BTLs) are among the most unusual lipids occurring in nature because of their presumed ability to span the entire membrane to form a monolayer structure. It is believed that because of their unique structural organization and chemical stability, BTLs offer extraordinary adaptation to archaea to thrive in the most extreme milieus. BTLs have also received considerable attention for development of novel membrane-based materials.

A Fluorogenic Pseudoinfection Assay to Probe Transfer and Distribution of Influenza Viral Contents to Target Vesicles.

Fusion of enveloped viruses with endosomal membranes and subsequent release of the viral genome into the cytoplasm are crucial to the viral infection cycle. It is often modeled by performing fusion between virus particles and target lipid vesicles. We utilized fluorescence microscopy to characterize the kinetic aspects of the transfer of influenza viral ribonucleoprotein (vRNP) complexes to target vesicles and their spatial distribution within the fused volumes to gain deeper insight into the mechanistic aspects of endosomal escape.

Membrane localization accelerates association under conditions relevant to cellular signaling.

Translocation of cytoplasmic molecules to the plasma membrane is commonplace in cell signaling. Membrane localization has been hypothesized to increase intermolecular association rates; however, it has also been argued that association should be faster in the cytosol because membrane diffusion is slow. Here, we directly compare an identical association reaction, the binding of complementary DNA strands, in solution and on supported membranes.

Critical Evaluation of Polarizable and Nonpolarizable Force Fields for Proteins Using Experimentally Derived Nitrile Electric Fields.

Molecular dynamics (MD) simulations are frequently carried out for proteins to investigate the role of electrostatics in their biological function. The choice of force field (FF) can significantly alter the MD results, as the simulated local electrostatic interactions lack benchmarking in the absence of appropriate experimental methods. We recently reported that the transition dipole moment (TDM) of the popular nitrile vibrational probe varies linearly with the environmental electric field, overcoming well-known hydrogen bonding (H-bonding) issues for the nitrile frequency and, thus, enabling the unambiguous measurement of electric fields in proteins ( , (17), 7562-7567).