The effect of increasing ionic strength on adenosylcobalamin-dependent methylmalonyl-CoA mutase from Propionibacterium shermanii was studied by using analytical ultracentrifugation. Both sedimentation-velocity and low-speed sedimentation-equilibration measurements show that the enzyme dissociates progressively into its two dissimilar subunits with increasing ionic strength. Equilibrium between ...

Knowledge of the ionic strength in cells is required to understand the in vivo biochemistry of the charged biomacromolecules. Here, we present the first sensors to determine the ionic strength in living cells, by designing protein probes based on Förster resonance energy transfer (FRET). These probes allow observation of spatiotemporal changes in the ionic strength on the single-cell level.

Hydrodynamic, spectroscopic, and chemical crosslinking studies on monomer chromatin subnits are reported as a function of ionic strength, pH, and temperature. In earlier studies, two salt-dependent conformational transitions were described (Gordon et al., Proceedings of the National Academy of Science, 75, 660, 1978). Transition one occurred between 0.7 and 2.0 mM ionic strength and transition ...

Pharmaceutical and personal care products (PPCPs) enter soils through reclaimed water irrigation and biosolid land applications. Colloids, such as clays, that are present in soil may interact with PPCPs and thus affect their fate and transport in the subsurface environment. This study addresses the influence of soil colloids on the sorption and transport behaviors of PPCPs through laboratory co...

Adenosine triphosphate has a dual effect on the incorporation of I-fluoro-2,4dinitrobenzene into myosin at low ionic strength: free ATP increases the incorporation, whereas magnesium-chelated ATP decreases it. Most of the reagent was incorporated into the smallest active fragment isolated from the stepwise digestion of the modified myosin with trypsin. Free ITP, GTP, CTP, UTP, ADP, PPPi, and PP...

Melittin is a cationic, amphipathic, hemolytic peptide composed of 26 amino acid residues. It is intrinsically fluorescent due to the presence of a single tryptophan residue, which has been shown to be crucial for its hemolytic activity. It undergoes a structural transition from a random coil monomer to an alpha-helical tetramer at high ionic strength. Although the aggregation behavior of melit...

The biochemical mechanism responsible for the osmotic sensitivity of glutamate oxidation in oyster (Crassostrea virginica Gmelin) gill mitochondria was examined. The relative roles of osmotically induced changes in matrix divalent cation concentration and ionic strength were determined. The calcium-magnesium ionophore A23187 inhibited glutamate oxidation in both low(40% of control rate) and hig...

The accuracy of many convenient methods for determining the proportion of hemoglobin A1 to total hemoglobin by ion-exchange chromatography is in question because those methods have not been evaluated against a reference method. In addition, several if not all of these tests are influenced by laboratory temperature. We modified the chromatographic conditions usually used, to arrive at a method t...

With the constant development of new ionic liquids, the understanding of the chemical fate of these compounds also needs to be updated. To this effect, the interaction of a number of novel ionic liquids with soils was determined. Therefore, three novel headgroups (ammonium, phosphonium, or pyrrolidinium) with single or quaternary substitution were tested on a variety of soils with high-to-low o...

The flow-injection analysis (FIA) method has long been used for the quantitative determination of b-glucans. FIA makes use of the enhanced fluorescence produced when b-glucan forms complexes with Calcofluor. For successful application of this analysis method, the lowest molecular weight (MW) in the sample has to be higher than a critical MW below which the fluorescence intensity of the complex ...