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At least 757 records · Page 42Linked to original sources
PubMed1984

Microcin 7: purification and properties.

Microcin 7 is an antibiotic peptide, produced and excreted to the culture medium by E. coli strains harboring the plasmid pRYC7. This peptide was extracted from the culture media by adsorbing it on octadecyl silica. It was purified by gel filtration on Sephadex G-25 and reverse phase high performance liquid chromatography. Its amino acid composition is the following: Ala (0.8), Arg (1.9), Asx (1.9), Gly (1.5), Met (0.8) and Thr (0.9). The purified peptide dose not react with ninhydrin and it is resistant to carboxypeptidase degradation, indicating that the molecule may be a cyclic or end-blocked oligopeptide.

Amino Acids↗
PubMed1978

Isolation, purification, and partial chemical characterization of chromium(III) fractions existing in brewer's yeast and Sabouraud's liquid medium.

An ethanol extract of brewer's yeast which had been cultivated in a medium containing trivalent 51Cr was analyzed for 51Cr compounds by using petroleum ether extraction, gel filtration, cation and anion exchange chromatography and thin layer chromatography. Similar analytical procedures as for the above analysis were used for studying 51Cr compounds formed in the spent culture medium and in a sterile medium. Several 51Cr fractions were isolated from the three chromium sources, but one anionic 51Cr fraction present in the yeast and in the spent culture medium was not found in the sterile medium. Molecular weight estimations of the 51Cr fractions by gel filtration chromatography showed that the 51Cr ion exchange fractions contained several 51Cr compounds. The molecular weights of these compounds ranged from 150 to 1000 daltons and the molecular weights of 51Cr compounds separated from the yeast were markedly lower than those of the corresponding ion exchange fractions isolated from the culture medium. By using thin layer chromatography it was possible to isolate 51Cr compounds from the main bulk of ninhydrin active impurities. The polarity of all 51Cr compounds was found to be greater than that of most amino acids. The 51Cr compounds isolated from the yeast were mixed with 125I-insulin and incubated, after which the solution was eluted through Sephadex G-50 gel to test if binding had occurred. Elution peaks of 51Cr and 125I-insulin showed that 51Cr compounds were not bound to the insulin.

Chromium↗
PubMed1987

Evidence for structural changes in dermatan sulfate and hyaluronic acid with aging.

Three dermatan sulfates (DS18, DS28, and DS35) were isolated from women's skin of ages 19 +/- 2.5, 35 +/- 3.5, 47 +/- 1.7, 60 +/- 0.8, and 75 +/- 5 years. They sequentially precipitated with 18, 28, and 35% ethanol. Their sulfate content was: 23.5, 25.3, and 29.0% (w/w) for DS18 at ages 19-35, 47, and 60 years, respectively; 29.0, 24.0, and 18.8% for DS28; and 18.0, 20.0, and 20.6% for DS35 at ages 19-47, 60, and 75 years, respectively. Both DS18 and DS28 decreased, respectively, from 0.030% (of wet-skin weight) to traces at age 75, and from 0.020 to 0.010% at 60 years. At age 75, DS28 apparently increased by 30%. The DS35 values (traces-0.006%) had no age-related trend. Hyaluronic acid (HA) precipitated with 45% ethanol, was 0.030% of skin-weight at ages 19-47, and decreased to 0.015 and 0.007% at 60 and 75 years, respectively. Its electrophoretic mobility was slower at age 47. In the oldest group, i.r. spectra of HA and DS35 displayed no bands at 1650-1600, 1380, and 1320 cm-1, and a new band at 1560 cm-1. Moreover, ninhydrin-positive material of HA and DS35 increased by 75 and 95%, respectively, and the reducing GlcNAc content of HA decreased. These data showed three chemically different dermatan sulfates (two of which were preponderant) and N-deacetylation of HA and DS35 of the oldest group. After age 47, total DS and HA considerably decreased, DS18 and DS35 were oversulfated, and DS28 became undersulfated with aging.

Adult↗
PubMed1997

Comparison of four different phenylalanine determination methods.

The ISOLAB NCS phenylalanine determination kit has not been widely applied for neonatal screening and patient follow up in Europe until now. This method, based on fluorescence enhancement of a phenylalanine-ninhydrin reaction product by the dipeptide L-leucyl-L-alanine, was compared with three other procedures: (1) The Quantase kit (Shield Diagnostics) for enzymatic determination of phenylalanine, (2) the standard amino acid analysis by means of ion exchange chromatography, and (3) the Guthrie Test as a bacterial inhibition assay (BIA). Only authentic samples from PKU patients were evaluated: once with the NCS kit and at least once with one of the three other methods. There was good agreement between the results obtained by the NCS kit using dried blood specimens and either of the other three methods, as well as between the NCS kit using plasma samples and the Quantase kit and ion exchange chromatography. Plasma sample measurement by NCS proved advantageous because of the option of measuring each microtiter plate twice by resetting the calibrators, i.e. special standards for plasma samples could be used on the same plate. We conclude that this method should prove time saving and cost effective when both neonatal screening and patient follow up are carried out in the same laboratory.

Humans↗
PubMed1975

A reliable method for the simultaneous estimation of dopamine, noradrenaline and serotonin in discrete areas of brain.

1. Sub-microgram levels of dopamine (DA), noradrenaline (NA) and serotonin (5HT) were estimated simultaneously in small discrete areas of brain by a simple combined alumina adsorption-spectrofluorometric technique. 2. The method does not depend on the use of ninhydrin which is reported to interfere with the spectrofluorometric assay of 5HT nor does the method involve the use of phosphate buffers which reportedly are a source of error in catecholamine assays. 3. The method described is suitable for the measurement of amine levels both in normal conditions and when amino levels have been severly reduced by amine-depleting drugs. Neither reserpine nor alpha-methyl-p-tyrosine interfere in the assay.

Animals↗
PubMed1977

Ornithine methyl ester. An unusual metabolite encountered in the urine of patients with a urea cycle disorder characterized by hyperammonemia, hyperornithinemia and homocitrullinuria.

In the urine of six subjects with a urea cycle disorder characterized by hyperammonemia, hyperornithinemia and homocitrullinuria, an unusual ninhydrin-reaction compound was encountered. This unknown on hydrolysis yielded ornithine as the only amino acid and, on dansylation studied, yielded didansyl ornithine. The metabolite from urine has been shown to have the same chromatographic mobility as ornithine methyl ester on paper cellulose thin layer, and ion exchange chromatography. When trimethylsily derivatives were prepared the unknown and the ornithine methyl ester standard had similar mobility on gas chromatography. Identification of the unknown as the ornithine methyl ester was confirmed by gas chromatography-mass spectrometric analysis. In the patients' urines the concentration of methyl ornithine ranged from 70 to 368 microne moles/g creatinine.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

Automated triple assay for proline, hydroxyproline and hydroxylysine on one single sample.

1. A new, quick, sensitive and specific assay for the quantitative determination of proline is presented together with its automatization. The use of glacial acetic acid-formaldehyde as the solvent for ninhydrin lends a series of advantages to the reaction. 2. A serial automated procedure for the simultaneous detection of proline, hydroxyproline and hydroxylysine in one single sample is pesented. The advantage of the triple assay lies in the use of one single sample instead of three previously aliquoted fractions in three individual automated assays. The triple assay is as specific, reproducible and sensitive as the individual assays. 3. A quick, manual assay for hydroxylysine is presented. This method represents a further simplifiction of previous ones by the same author and adds the advantage of rapidity to their sensitivity and specificity.

Adolescent↗
PubMed2000

Comparison of the thin-layer chromatographic properties of sulfur-containing amino acids and their aminophosphonic analogues.

The thin-layer chromatographic behavior of the natural, sulfur-containing amino acids (Cys, Hcys, Met) and their phosphonic analogues (CysP, HcysP, MetP) has been studied. Their detection limits using iodine and molybdate, ninhydrine and iodine-azide reagents were determined, and the R(F) values of these two classes of amino acids in acidic, neutral and mild basic solvent systems were compared.

Amino Acids↗
PubMed1980

Separation of amino sugars and related compounds by two-dimensional thin-layer chromatography.

Separation of amino compounds, including galactosamine and glucosamine, found in lipopolysaccharide and peptidoglycan, can be accomplished by two-dimensional thin-layer chromatography on cellulose layers. The solvent systems used are: 2-propanol-90% formic acid-water (80:4:20,v/v) in the first dimension and lutidine-water (65:35, v/v) in the second dimension. Compounds were detected using a chromogenic ninhydrin spray.

Chromatography, Thin Layer↗
PubMed1976

Quantitative determination of hexosamines in glycoprotein by ion-exchange chromatography.

An ion-exchange chromatographic method for the quantitative determination of glucosamine and galactosamine in glycoproteins is described. The hexosamines are completely separated from interfering peptides of the acid hydrolysate using a small column of cation exchanger in a manner described earlier by Boas. Chromatographic separation of the hexosamine fraction and the determination of glucosamine and galactosamine are accomplished on an amino acid analyzer with ninhydrin.

Chromatography, Ion Exchange↗
PubMed1981

Determination of the relative amounts of the B and C components of neomycin by ion-exclusion chromatography using refractometric detection.

Refractometric detection can be used as a convenient alternative to ninhydrin colorimetric or polarimetric detection in ion-exclusion chromatography of neomycinn. The determination of the relative amounts of neomyci B and C using different detection methods is examined. The use of a resin of smaller granulometry and a medium-pressure chromatographic apparatus reduces the analysis time to less than 25 min.

Chromatography, Gel↗
PubMed1976

Computerized data analysis of amino acids in physiologic fluids.

A Fortran IV computer program is described which identifies, computes, and statistically evaluates amino acid concentrations determined by an automatic amino acid analyzer in physiologic fluids. The program accepts retention time and intergrated peak areas from two calibration standards for identification and computational reference. Two internal standards are used to compensate for variations in injector performance and ninhydrin decay. Calibration standard responses are statistically treated to assist in detection of equipment malfunction. The statistical data base is automatically explanded through inclusion of data from normal patients. Amino acid concentrations are printed with appropriate mean and standard deviation values in a format acceptable as a final report.

Amino Acids↗
PubMed1986

Determination of biogenic amines in cheese and some other food products by high-performance liquid chromatography in combination with thermo-sensitized reaction detection.

A simple high-performance liquid chromatographic (HPLC) analysis is described for biogenic amines in cheese and other food products. The sample clean-up consists of a precipitation-extraction step with trichloroacetic acid, which gives recoveries of amines in cheese in the range of 85-105%. The HPLC analysis is performed by reversed-phase ion-pair chromatography, using a ninhydrin-containing eluent, which eliminates the need for an extra reagent pump for the post-column derivatization. Band broadening is minimized by using a poly(tetrafluoroethylene) knitted tube reactor at 145 degrees C. The detection limit for amines is 2 mg/kg cheese and the method is linear for 0.1-4 micrograms of amine injected. Examples are given of the analysis of amines in cheese, wine and sauerkraut.

Biogenic Amines↗
PubMed1988

The peptide toxin of the cyanobacterium Microcystis aeruginosa PCC 7941. Isolation and analysis by nuclear magnetic resonance and fast atom bombardment mass spectroscopy.

Toxin was obtained from the cyanobacterium Microcystis aeruginosa PCC7941 by extracting freeze-dried cells with water-saturated, acidified n-butanol, diethyl ether-water distribution, reversed-phase thin-layer chromatography and silica high-performance liquid chromatography (HPLC). Two toxic peptide fractions resulted from HPLC. One of these fractions was analyzed by UV and NMR spectroscopy, amino acid analysis and fast atom bombardment mass spectroscopy. The following amino acid analysis and fast atom bombardment mass spectroscopy. The following amino acids were identified: beta-methyl-Asp, Thr, Glu, Ala, Val, Leu, Phe, Arg, N-methyldehydro-Ala and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid. Yet the mass spectroscopic data showed that the fraction was still composed of several, most likely cyclic peptides that did not stain with ninhydrin.

Amino Acids↗
PubMed1990

High-performance liquid chromatographic determination of an arginine-containing octapeptide antagonist of vasopressin in human plasma by means of a selective post-column reaction with fluorescence detection.

A novel high-performance liquid chromatographic method was developed for the determination in plasma samples of the synthetic octapeptide SK&F 105494 (O-ethyl-D-tyrosyl-L-phenylalanyl-L-valyl-L-asparaginyl-5-[1- (carboxymethyl)cyclohexyl]-L-norvalyl-L-arginyl-D-arginamide , cyclic (5-1) peptide), an active aquaretic agent which significantly increases water excretion in experimental animal models through competitive antagonism of renal epithelial vasopressin receptors. The method involves isolation of Sk&F 105494 from plasma samples by solid phase extraction prior to chromatographic analysis. Following chromatographic separation, in-line fluorescence detection was accomplished via a selective-post-column reaction of the guanidino group of the arginine moiety of the peptide with alkaline ninhydrin to generate a highly fluorescent product. Optimization of the post-column reaction conditions and the use of high-performance liquid chromatography columns of reduced internal diameter (2.1 mm), resulted in an on-column detection limit of 50 pg (45 fmol). The limit of sensitivity in plasma was 0.5 ng/ml. The assay was linear over the range 0.5-100 ng/ml. Precision and accuracy were within 11% across the calibration range. The assay was shown to be suitable to study the pharmacokinetics of SK&F 105494 in human subjects and animals. In addition, the methodology developed has general applicability in the detection of arginine-containing peptides in biological matrices.

Arginine↗
PubMed1984

Measurement of hydroxylysine glycosides in urine and its application to spinal cord injury.

A new technique to evaluate the degradation of skin or bone collagen by measuring glucosylgalactosyl hydroxylysine and galactosyl hydroxylysine is presented. The method utilizes an automated amino acid analyzer. Eluents used are lithium buffers, and the color reagent is ninhydrin. Both glycosides elute in 3.5 h. Samples require minimum preparation. Urinary concentrations of both glycosides in ten patients with cervical spinal cord injuries of less than six months duration were higher than in five healthy controls. Proportional increases were different for each of the two glycosides. Variations in the proportional increase of each glycoside indicate different rates of degradation of skin and bone collagen. Repeated evaluations of the two urinary glycosides may help to predict whether patients are likely to develop skin- or bone-related clinical complications.

Adult↗
PubMed1984

Combination of conventional and high-performance liquid chromatographic techniques for the isolation of so-called "uraemic toxins".

Using fluids from the artificial kidney as an example, a generally useful combination of separation techniques is described for the preparative isolation of biologically active subfractions from extremely heterogeneous and diluted biological fluids. Haemofiltrate (20 l) and dialysate (100 l), respectively, are desalted and concentrated in one step by reverse osmosis using membranes with a nominal cut-off of 500 Daltons. The retentate with high concentrations of "uraemic toxins" is fractionated by preparative ion-exchange chromatography (double column technique with detection at 206 nm) and size exclusion chromatography yielding large amounts of ninhydrin-positive subfractions which inhibit DNA synthesis of rat bone marrow and HeLa cells in vitro, respectively. These fractions were analyzed by reversed-phase and size exclusion high-performance liquid chromatography. Many of the isolated fractions were shown to contain peptides.

Animals↗
PubMed1983

Improved cost effective thin-layer detection techniques for routine surveillance of commonly abused drugs in drug abuse urine screening and proficiency testing programs with built-in quality assurance.

Improved, sensitive, reliable and cost effective thin-layer detection procedures for poly-drug usage (12-15 drug evaluations per specimen) are presented. Extraction procedures using ion-exchange resin loaded paper and liquid-liquid extraction with the built-in quality assurance program are reported. The combined use of ninhydrin-fluorescamine detection reagent for the identification of various central nervous system stimulants is only one of the several modifications and improvements made during the past 14 years. Laboratories, participating in proficiency testing programs in drug abuse toxicology monitoring are encourage the use of proposed extraction and identification techniques.

Chromatography, Paper↗