Hyperthermophilic proteins often possess an increased number of surface salt bridges compared with their mesophilic homologues. However, salt bridges are generally thought to be of minor importance in protein stability at room temperature. In an effort to understand why this may no longer be true at elevated temperatures, we performed molecular dynamics simulations of the hyperthermophilic prot...

1. The commonly used method of passing short-circuit current (/sc) across insect epithelia through Ag-AgCl electrodes, without the use of salt bridges, leads to significant OH~ production at the cathode (lumen side) when high currents are applied. 2. The alkalization of the lumen previously reported when cyclic AMP was added to short-circuited locust hindgut is a result of this phenomenon rathe...

An experimental approach to evaluate the net binding free energy of buried hydrogen bonds and salt bridges is presented. The approach, which involves a modified multiple-mutant cycle protocol, was applied to selected interactions between TEM-1-beta-lactamase and its protein inhibitor, BLIP. The selected interactions (two salt bridges and two hydrogen bonds) all involving BLIP-D49, define a dist...

absorbed in the atmosphere, the NIR water vapor bands. Thus, we see no way of defending Stephen's statement that conclusions based on broad-band measurements (1) are inconsistent with other existing data sets where discrepancies were found to occur between measurements in spectral bands and theory. Instead, the broad-band solar absorption findings presented in our report (1) are entirely consis...

The dimerization specificity of the bZIP transcription factors resides in the leucine zipper region. It is commonly assumed that electrostatic interactions between oppositely charged amino acid residues on different helices of the leucine zipper contribute favorably to dimerization specificity. Crystal structures of the GCN4 leucine zipper contain interhelical salt bridges between Glu20 and Lys...

We estimate the free energies of transfer of ionized amino acid side chains in water to both their ion-paired and neutral hydrogen-bonded states in low-dielectric media. The difference between the two free energies corresponds to the proton transfer free energy in a "salt bridge" formed between acidic and basic groups (i.e., lysine and glutamic acid residues). Our approach is to use gas phase p...

The prevalence of salt bridges across protein binding interfaces is surprising given the significant costs of desolvating the two charged groups upon binding. These desolvation costs, which are difficult to examine using laboratory experiments, have been computed in previous studies using the Poisson-Boltzmann (PB) implicit solvent model. Here, for the first time, we directly compare the PB imp...

Human Rad52 (hRad52) and Rad51 (hRad51) proteins are important components of homologous recombination machinery involved in DNA double strand break repair. hRad52 subunits oligomerize to form rings, which are further believed to stack one over another giving rise to higher order structures. Such structures bind the ends of duplex DNA to bring about DNA end joining. hRad51 exists in the native s...

The force-induced detachment of the adhesion protein complex CD2-CD58 was studied by steered molecular dynamics simulations. The forced detachment of CD2 and CD58 shows that the system can respond to an external force by two mechanisms, which depend on the loading rate. At the rapid loading rates of 70 and 35 pN/ps (pulling speeds of 1 and 0.5 Å/ps) the two proteins unfold before they separate,...