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At least 289 records · Page 16Linked to original sources
PubMed1994

Analysis of dicamba degradation by Pseudomonas maltophilia using high-performance capillary electrophoresis.

A method based on high-performance capillary electrophoresis (HPCE) was developed for the simultaneous analysis of dicamba and its metabolites in media containing the bacterium Pseudomonas maltophilia. Dicamba, 3,6-dichlorosalicylic acid (DCSA), and related products were extracted from media samples using ether under acidic conditions and injected onto an HPCE system containing a pH 10.0 running buffer. Baseline resolution between these compounds was obtained at 30 kV with a total run time of 6 min on a 50-microns i.d. x 50-cm capillary. The linear range for dicamba and DCSA detected at 274 nm extended from 0 to 100 mg/liter and the dynamic range for both compounds extended to 2000 mg/liter. The within-run precision was +/- 5% or less throughout the entire concentration range studied. The limits of detection for dicamba and DCSA in the media samples were 6 and 2 mg/liter. This corresponded to detection limits of 0.3 and 0.1 ng, respectively, in the injected extracts. With this method it was possible to conduct preliminary studies examining the kinetics of dicamba metabolism in P. maltophilia.

Capillary Action↗
PubMed1994

The effect of phytic acid on the resolution of peptides and proteins in capillary electrophoresis.

Studies are reported on the effect of the sodium salt of phytic acid on the resolution of peptides and proteins. Improved separation in the case of peptides is shown to be due to ion-ion pairing interactions between the positively charged peptides and the phytic acid polyanionic species. The improved peak shapes related to the proteins can be interpreted in terms of the sample preconcentration due to injection of analytes from a water medium to one of high ionic strength.

Amino Acid Sequence↗
PubMed1994

A capillary electrophoresis-based assay for protein kinases and protein phosphatases using peptide substrates.

A novel procedure for detection and assay of protein kinase and phosphatase activities in complex biological mixtures was developed. By means of capillary zone electrophoresis (CZE) methodology, the phosphorylated and dephosphorylated forms of the peptide Kemptide, a 46-amino-acid fragment from protein phosphatase inhibitor-1 and a peptide fragment corresponding to the RII subunit of cAMP-dependent protein kinase (PKA), were rapidly resolved. This facilitated nonradioactive detection of PKA and protein phosphatase-2B (calcineurin) in rabbit skeletal muscle extracts. In addition, the CZE procedure enabled a site-specific assay of a 14-amino-acid peptide from the glycogen-binding subunit of protein phosphatase-1 monophosphorylated on distinct sites by PKA and casein kinase-II. These results suggest that CZE may prove to be extremely useful for the analysis of peptides that are phosphorylated at multiple sites in vivo.

Animals↗
PubMed1994

Comparison of the separation of proteins by sodium dodecyl sulfate-slab gel electrophoresis and capillary sodium dodecyl sulfate-gel electrophoresis.

Capillary sodium dodecyl sulfate-gel electrophoresis, a one-dimensional version of the well-established planar analytical method of SDS-polyacrylamide gel electrophoresis, has proven a powerful new microanalytical method for the separation of protein molecules according to their size. In this paper the planar SDS-PAGE and the capillary SDS-gel electrophoresis of different proteins are compared with respect to performance, precision, and efficiency. Molecular weight versus migration distance and migration time curves for 65 proteins, running from 14,200 to 205,000 Da, are given for both methods.

Capillary Action↗
PubMed1994

One-hour downward capillary blotting of RNA at neutral pH.

This report describes a setup for the downward capillary blotting of RNA with the use of 10 x SSC as a transfer solution. The setup is composed of a stack of blotting papers, hybridization membrane, and agarose gel. Two layers of blotting paper connect the stack with two reservoirs containing transfer solution. Using this setup, blotting of RNA fragments (< 7.5 kb) can be completed in 1 h. If necessary, the blotting time can be expanded from 1 to 18 h without decrease in hybridization efficiency of RNA.

Actins↗
PubMed1995

A capillary zone electrophoresis assay for the nucleoside transfer enzyme adenosine diphosphate-glucose pyrophosphorylase.

Conditions are described for a capillary zone electrophoresis-based assay of ADP-glucose pyrophosphorylase, the first enzyme in the de novo synthesis for alpha-glucan synthesis in plants and bacteria. ATP, ADP-glucose, and other adenine derivatives are effectively resolved and quantified in 12 min of electrophoresis. The method requires minimal sample manipulations and no postincubation hydrolyses, is effective over a wide range of enzyme and substrate concentrations, has a sensitivity comparable to radioisotope assays, and yields reproducible results in either the forward and reverse directions. Moreover, the assay is applicable to other enzymes that utilize nucleosides or their bases as substrates or products.

Adenine Nucleotides↗
PubMed1995

Characterization of glycopeptides from recombinant coagulation factor VIIa by high-performance liquid chromatography and capillary zone electrophoresis using ultraviolet and pulsed electrochemical detection.

Four glycopeptide (GP) fractions containing glycosylated Asn 322 were isolated from a tryptic digest of recombinant coagulation factor VII by reversed-phase-HPLC (RP-HPLC). Characterization of the GPs by enzymatic desialylation and RP-HPLC as well as by enzymatic deglycosylation, RP-HPLC, and high-pH anion-exchange chromatography indicated that the four GPs consisted of the same decapeptide but with 0, 1, 2, or 4 residues of sialic acid. In comparison to HPLC, capillary zone electrophoresis (CZE) using uv and pulsed electrochemical detection (PED) afforded improved separation of GPs from each other and from contaminants. CZE-uv and CZE-PED of the desialylated GPs and deglycosylated GPs corroborated the results obtained with the chromatographic methods.

Amino Acid Sequence↗
PubMed1995

Preparative and analytical capillary zone electrophoresis analysis of native endorphins and enkephalins extracted from the bovine pituitary: mass spectrometric confirmation of the molecular mass of leucine enkephalin.

One proopiomelanocortin peptide [beta-endorphin (BE)] and two proenkephalin A peptides [methionine enkephalin (ME) and leucine enkephalin (LE); LE derives also from proenkephalin B] were searched for in a bovine pituitary extract by capillary zone electrophoresis (CZE) and liquid secondary-ion mass spectrometry (LSIMS). A bovine pituitary homogenate was subjected to acid precipitation/centrifugation and solid-phase extraction of peptides using an octadecyl-silyl disposable cartridge. The peptide-enriched fraction was subjected to CZE at pH 2.5 and at pH 5.5., and fractions were collected under preparative CZE conditions within defined time windows where synthetic BE, ME, and LE migrate. The resolving power of CZE was demonstrated by collecting biological fractions at pH 5.5 under preparative conditions and by subsequently analyzing these fractions at pH 2.5 under analytical conditions. Preparative CZE was further performed at pH 2.5 for fractions collected at pH 5.5. LSIMS analysis of this second-dimensional CZE fraction revealed the appropriate protonated molecule ion [(M + H)+, m/z 556.4] of LE.

Animals↗
PubMed1995

Analysis of monoclonal antibody chimeric BR96-doxorubicin immunoconjugate by sodium dodecyl sulfate-capillary gel electrophoresis with ultraviolet and laser-induced fluorescence detection.

Sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CAGE), the capillary version of SDS-polyacrylamide-based slab gel electrophoresis, has been utilized for the separation and analysis of monoclonal antibody chimeric BR96 and the corresponding immunoconjugate prepared between BR96 and the anticancer drug doxorubicin (BR96-DOX). SDS-CAGE was performed in a coated capillary column filled with a polymer solution-based gel network matrix. Two detection formats, a uv absorbance detector and an argon-ion laser-based fluorescence detector, were incorporated into this system, providing complementary information for the determination of conjugated species. Both monoclonal antibody and immunoconjugates were studied in their native, denatured, and denatured and reduced states, respectively. Six peaks were identified following separation of the denatured BR96-DOX. These peaks were confirmed to correspond to all the possible conjugated species as expected. Analysis of the resulting "fingerprint" maps indicated that the light, heavy, and light-heavy chain conjugates are the predominant species. SDS-CAGE offers an alternative approach to the conventional slab gel electrophoresis and other chromatographic techniques, providing rapid, efficient, sensitive, and accurate information for the analysis of antibody and bioconjugates.

Antibodies, Monoclonal↗
PubMed1997

Determination of viridicatin in Penicillium cyclopium by capillary gas chromatography.

A sensitive gas chromatographic method for the determination of the quinoline alkaloid viridicatin, a fungal metabolite isolated from several Penicillium species and presumably a biogenetic precursor to naturally occurring diazepam-like 1,4-benzo-diazepines, has been developed. Prior to conversion of viridicatin into a volatile trimethylsilyl derivative, a rapid sample clean-up was accomplished by solid-phase extraction from mould mycelium on a C18 cartridge. Using synthetical 6-bromo-viridicatin as an internal standard, the amount of viridicatin produced de novo in emerged grown cultures of Penicillium cyclopium strain SM 72 was calculated in correlation to the duration of mould cultivation.

Benzodiazepines↗
PubMed1994

Microinjection technique: routine system for characterization of microcapillaries by bubble pressure measurement.

Five tubing types with different outer and inner diameter dimensions were used to pull injection capillaries with different openings. The correlation between threshold bubble pressure and tip inner and outer diameter was established for each type of tubing. Statistical analysis revealed that the bubble pressure is an accurate measure for the tip inner diameter independent of the tubing used to pull the capillary. A graph directly relating the tip inner diameter to the threshold bubble pressure is presented. The tip outer diameter could not be related to the bubble pressure for tubings of different size. This diameter depends on the wall thickness of the tubing and the puller configuration. Data on the inner tip diameter were used to test the relationship between volume released from injection capillaries and their tip radius. It was found that the volume increases with the fourth power of the radius. Strategies for optimizing the injection capillary are discussed.

Capillary Action↗
PubMed1993

Forces involved in length changes of cochlear outer hair cells.

Motion or force generation of outer hair cells may contribute to active modulation of cochlear mechanics. In order to determine the force involved in length changes of outer hair cells, a new in vitro method was used. In the first series of experiments, apical and basolateral extracellular spaces of outer hair cells of the guinea-pig cochlea were separated. Changes of the voltage between the two extracellular spaces induced reversible, proportional changes of the cell length of 4.4 nm/mV if the cell had a length of 80 microns. In the second series of experiments, cell elongations in response to negative pressure applied to the basal end of the cells were measured and corrected for frictional effects. From these data, the compliance of the longitudinal axis of the hair cells was calculated. It was 220 +/- 130 m/N (n = 25) and 240 +/- 170 m/N (n = 24) for cells of the third and fourth cochlear turns, respectively, if the water permeability of the cell membrane was neglected. If the water permeability was taken into account, the compliance was probably around 500 m/N [corrected]. Thus, a mechanism that changes the cell length by 1 microm must generate a static force of at least around 2 nN in an outer hair cell of the organ of Corti [corrected]. Electromotility of outer hair cells, induced by changes of the electrical potential difference across the outer hair cell, is a mechanism that generates this force.

Animals↗
PubMed1995

Effects of chronic low frequency stimulation on structural and metabolic properties of hindlimb suspended rat soleus muscle.

The use of chronic low frequency stimulations (CLFS, 10 Hz bipolar current 8 h.day-1) as a countermeasure against unweighting-induced muscle alterations was investigated in rat soleus muscle during 21 days of hindlimb suspension (HS). It was shown that CLFS was able to minimize the soleus muscle atrophy induced by suspension (-29% in stimulated muscles compared to -56% in the non-stimulated soleus muscle). In parallel, CLFS partly prevented the HS-induced decreases in the cross-sectional area of type I fibres and in the total and myofibril protein contents. Stimulation at low frequency reduced the increase in the fast-myosin expression recorded with unweighting. Moreover, the HS-induced increase in glycolytic capacity was counteracted to a considerable extent by CLFS. In conclusion, the results of this study showed that CLFS can only partly prevent the HS-induced modifications in the soleus muscle. However, the limited effectiveness of CLFS to prevent muscle atrophy emphasized the critical role of reduced load bearing in the induction of soleus muscle atrophy.

Animals↗