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Ionic Strength Solution (ionic + strength_solution)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Fast and novel purification method to obtain the prostate specific antigen (PSA) from human seminal plasma

THE PROSTATE, Issue 10 2006
Boris Acevedo
Abstract Background Prostate specific antigen (PSA) is a relevant antigen in diagnosis; follow-up, and therapeutic approaches for fighting the prostate cancer. Several methods have been published previously to obtain a high purity preparation of PSA. In general, these methods are expensive, time-consuming, laborious, and in some cases produce low yields. Methods Based on a panel of 7 anti-PSA Mab's we carried on binding and elution experiments of PSA antigen in 96-well plates. The selected Mab were immobilized in a Sepharose CL-4B activated matrix with the purpose of purify PSA from human seminal fluid. In order to optimize the purification procedure, we test several washing and elution conditions (chaotropic agents, high ionic strength solution, and extreme pH). Results We selected a high ionic strength solution (2 M MgCl2) as elution condition, and a previous washing step with a mix of two ionic solutions (2.5 M NaCl pH 8/1 M MgCl2 pH 5.5) in order to purify PSA. Using such conditions we obtained a PSA preparation with 90% of purity and 50% of recovery. Conclusion In this article, we report a simple, quickly, and non-expensive procedure to obtain free-PSA from human seminal plasma at high purity levels. Prostate 66: 1029,1036, 2006. © 2006 Wiley-Liss, Inc. [source]

Electric field induced desorption of bacteria from a conditioning film covered substratum

BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2001
Albert T. Poortinga
Abstract Desorption of three oral bacterial strains from a salivary conditioning film on an indium tin oxide electrode during application of a positive (bacterial adhesion to the anode) or a negative electric current was studied in a parallel plate flow chamber. Bacterial adhesion was from a flowing suspension of high ionic strength, after which the bacterial suspension was replaced by a low ionic strength solution without bacteria and currents ranging from ,800 to +800 ,A were applied. Streptococcus oralis J22 desorbed during application of a positive and negative electric current with a desorption probability that increased with increasing electric current. Two actinomyces strains, however, could not be stimulated to desorb by the electric currents applied. The desorption forces acting on adhering bacteria are electroosmotic in origin and working parallel to the electrode surface in case of a positive current, whereas they are electrophoretic and electrostatic in origin and working perpendicular to the surface in case of a negative current. By comparison of the effect of positive and negative electric currents, it can be concluded that parallel forces are more effective in stimulating bacterial desorption than perpendicular forces. The results of this study point to a new pathway of cleaning industrial and biomedical surfaces without the use of detergents or biocides. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 395,399, 2001. [source]

Charges dispersed over the permeation pathway determine the charge selectivity and conductance of a Cx32 chimeric hemichannel

THE JOURNAL OF PHYSIOLOGY, Issue 10 2008
Seunghoon Oh
Previous studies have shown that charge substitutions in the amino terminus of a chimeric connexin, Cx32*43E1, which forms unapposed hemichannels in Xenopus oocytes, can result in a threefold difference in unitary conductance and alter the direction and amount of open channel current rectification. Here, we determine the charge selectivity of Cx32*43E1 unapposed hemichannels containing negative and/or positive charge substitutions at the 2nd, 5th and 8th positions in the N-terminus. Unlike Cx32 intercellular channels, which are weakly anion selective, the Cx32*43E1 unapposed hemichannel is moderately cation selective. Cation selectivity is maximal when the extracellular surface of the channel is exposed to low ionic strength solutions implicating a region of negative charge in the first extracellular loop of Cx43 (Cx43E1) in influencing charge selectivity analogous to that reported. Negative charge substitutions at the 2nd, 5th and 8th positions in the intracellular N-terminus substantially increase the unitary conductance and cation selectivity of the chimeric hemichannel. Positive charge substitutions at the 5th position decrease unitary conductance and produce a non-selective channel while the presence of a positive charge at the 5th position and negative charge at the 2nd results in a channel with conductance similar to the parental channel but with greater preference for cations. We demonstrate that a cysteine substitution of the 8th residue in the N-terminus can be modified by a methanthiosulphonate reagent (MTSEA-biotin-X) indicating that this residue lines the aqueous pore at the intracellular entrance of the channel. The results indicate that charge selectivity of the Cx32*43E1 hemichannel can be determined by the combined actions of charges dispersed over the permeation pathway rather than by a defined region that acts as a charge selectivity filter. [source]

Development of a method to assess binding of astaxanthin to Atlantic salmon Salmo salar L. muscle proteins

AQUACULTURE RESEARCH, Issue 4 2005
Madhury R Saha
Abstract Several methods were examined to characterize the binding between astaxanthin and salmon muscle protein(s) in order to provide tools for evaluation of the role of muscle proteins on astaxanthin retention in Atlantic salmon Salmo salar L. flesh. The methods included gel filtration chromatography, displacement of a hydrophobic probe and ultrafiltration. With gel filtration chromatography, aggregation of astaxanthin under the experimental conditions was a major problem for the separation of bound astaxanthin from free astaxanthin because the apparent molecular weight of aggregated astaxanthin or astaxanthin micelles was in the range of protein,astaxanthin complexes. Displacement of the fluorescent probe 8-anilino-1-naphthalenesulphonate (ANS) was not effective as astaxanthin quenched the fluorophore so that displacement could not be observed. An ultrafiltration method was developed using 200-mM sodium cholate for dispersion of astaxanthin aggregates. This allowed unbound astaxanthin to be separated from bound astaxanthin using a 30-kDa filter. After salmon muscle proteins were solubilized in different fractions by sequential extraction using low ionic strength solutions, the astaxanthin binding of different fractions was assessed using the ultrafiltration method. The significant difference (P<0.05) observed in the astaxanthin binding of the various fractions suggests an application of this assay to detect differences in affinity of proteins for astaxanthin. The results also suggest that proteins other than actomyosin or actin can bind astaxanthin in Atlantic salmon flesh. This method can be used for the identification of astaxanthin-binding proteins in salmon flesh and other tissues. [source]