The transcription factor early growth response protein (EGR)1 orchestrates a plethora of signaling cascades involved in cellular homeostasis, and its downregulation has been implicated in the development of prostate cancer. Herein, using a battery of biophysical tools, we show that the binding of EGR1 to DNA is tightly regulated by solution pH. Importantly, the binding affinity undergoes an enh...

OmpF and OmpC porin channels are responsible for the passage of small hydrophilic solutes across the outer membrane of Escherichia coli. Although these channels are two of the most extensively studied porin channels, what had yet remained elusive was the reason why OmpC shows markedly lower permeability than OmpF, despite having little difference in its channel size. The OmpC channel, however, ...

Lipid nanoparticles (LNP) containing ionizable cationic lipids are the leading systems for enabling therapeutic applications of siRNA; however, the structure of these systems has not been defined. Here we examine the structure of LNP siRNA systems containing DLinKC2-DMA(an ionizable cationic lipid), phospholipid, cholesterol and a polyethylene glycol (PEG) lipid formed using a rapid microfluidi...

Ionizable cyclodextrins have attracted increasing attention in host-guest chemistry and pharmaceutical industry, mainly due to the introduction of favorable electrostatic interactions. The ionizable cyclodextrins could not only enhance its own solubility but also induce oppositely charged guests to form more stable complex. However, the aggregation induced by charged cyclodextrins has rarely be...

Address correspondence to P.W. Carr. hen preparing binary eluents containing both an organic solvent and a buffer for a buffer reversed-phase liquid chromatography (LC), one must know the solubility of the buffer in the organic cosolvent to avoid precipitation of the buffer salt. For example, one must know the highest percent organic cosolvent (that is, %B, v/v) in which a buffer salt remains s...

Pig heart isocitrate dehydrogenase, which catalyzes the TPN-dependent dehydrogenation of isocitrate as well as the decarboxylation of oxalosuccinate, is inactivated by treatment with iodoacetate at pH 5.5 and 30’. Approximately 1 mole of “C-labeled reagent is incorporated per mole of protein. The effect of alkylation on the isocitrate dehydrogenase activity is greater than that on the oxalosucc...

The zinc and cobalt forms of the prototypic gamma-carbonic anhydrase from Methanosarcina thermophila were characterized by extended X-ray absorption fine structure (EXAFS) and the kinetics were investigated using steady-state spectrophotometric and (18)O exchange equilibrium assays. EXAFS results indicate that cobalt isomorphously replaces zinc and that the metals coordinate three histidines an...

The rate-limiting step for nucleotide incorporation in the pre-steady state for most nucleic acid polymerases is thought to be a conformational change. As a result, very little information is available on the role of active-site residues in the chemistry of nucleotidyl transfer. For the poliovirus RNA-dependent RNA polymerase (3D(pol)), chemistry is partially (Mg(2+)) or completely (Mn(2+)) rat...

The association of complement component C3d with B or T cell complement receptor 2 (CR2 or CD21) is a link between innate and adaptive immunity. It has been recognized in experimental studies that the C3d-CR2 association is pH- and ionic strength-dependent. This led us to perform electrostatic calculations to obtain a theoretical understanding of the mechanism of C3d-CR2 association. We used th...