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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Protein Folding By 'Levels Of Separation': A Hypothesis, Lesley H. Greene, Terri M. Grant Jan 2012

Protein Folding By 'Levels Of Separation': A Hypothesis, Lesley H. Greene, Terri M. Grant

Chemistry & Biochemistry Faculty Publications

The protein folding process has been studied both computationally and experimentally for over 30 years. To date there is no detailed mechanism to explain the formation of long-range interactions between the transition and native states. Long-range interactions are the principle determinants of the tertiary structure. We present a theoretical model which proposes a mechanism for the acquisition of these interactions as they form in a modified version of ‘degrees of separation’, that we term ‘levels of separation’. It is based on the integration of network science and biochemistry. (C) 2012 Federation of European Biochemical Societies.


Inhibition Of Voltage-Gated Na+ Current By Nanosecond Pulsed Electric Field (Nspef) Is Not Mediated By Na+ Influx Or Ca²+ Signaling, Vasyl Nesin, Andrei G. Pakhomov Jan 2012

Inhibition Of Voltage-Gated Na+ Current By Nanosecond Pulsed Electric Field (Nspef) Is Not Mediated By Na+ Influx Or Ca²+ Signaling, Vasyl Nesin, Andrei G. Pakhomov

Bioelectrics Publications

In earlier studies, we found that permeabilization of mammalian cells with nsPEF was accompanied by prolonged inhibition of voltage-gated (VG) currents through the plasma membrane. This study explored if the inhibition of VG Na+ current (INa) resulted from (i) reduction of the transmembrane Na+ gradient due to its influx via nsPEF-opened pores, and/or (ii) downregulation of the VG channels by a Ca2+ -dependent mechanism. We found that a single 300?ns electric pulse at 1.65.3?kV/cm triggered sustained Na+ influx in exposed NG108 cells and in primary chromaffin cells, as detected by increased fluorescence of a …


Electric Field Exposure Triggers And Guides Formation Of Pseudopod-Like Blebs In U937 Monocytes, Mikhail A. Rassokhin, Andrei G. Pakhomov Jan 2012

Electric Field Exposure Triggers And Guides Formation Of Pseudopod-Like Blebs In U937 Monocytes, Mikhail A. Rassokhin, Andrei G. Pakhomov

Bioelectrics Publications

We describe a new phenomenon of anodotropic pseudopod-like blebbing in U937 cells stimulated by nanosecond pulsed electric field (nsPEF). In contrast to "regular," round-shaped blebs, which are often seen in response to cell damage, pseudopod-like blebs (PLBs) formed as longitudinal membrane protrusions toward anode. PLB length could exceed the cell diameter in 2 min of exposure to 60-ns, 10-kV/cm pulses delivered at 10-20 Hz. Both PLBs and round-shaped nsPEF-induced blebs could be efficiently inhibited by partial isosmotic replacement of bath NaCl for a larger solute (sucrose), thereby pointing to the colloid-osmotic water uptake as the principal driving force for bleb …


Oxidative Effects Of Nanosecond Pulsed Electric Field Exposure In Cells And Cell-Free Media, Olga N. Pakhomova, Vera A. Khorokhorina, Angela M. Bowman, Raminta Rodaitė-Riševičienė, Gintautas Saulis, Shu Xiao, Andrei G. Pakhomov Jan 2012

Oxidative Effects Of Nanosecond Pulsed Electric Field Exposure In Cells And Cell-Free Media, Olga N. Pakhomova, Vera A. Khorokhorina, Angela M. Bowman, Raminta Rodaitė-Riševičienė, Gintautas Saulis, Shu Xiao, Andrei G. Pakhomov

Bioelectrics Publications

Nanosecond pulsed electric field (nsPEF) is a novel modality for permeabilization of membranous structures and intracellular delivery of xenobiotics. We hypothesized that oxidative effects of nsPEF could be a separate primary mechanism responsible for bioeffects. ROS production in cultured cells and media exposed to 300-ns PEF (1–13 kV/cm) was assessed by oxidation of 2′, 7′-dichlorodihydrofluoresein (H2DCF), dihidroethidium (DHE), or Amplex Red. When a suspension of H2DCF-loaded cells was subjected to nsPEF, the yield of fluorescent 2′,7′dichlorofluorescein (DCF) increased proportionally to the pulse number and cell density. DCF emission increased with time after exposure in nsPEF-sensitive Jurkat …