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PubMed1976

Oxidative side reactions during dansylation of SH-compounds.

Dansyl chloride can act as an oxidizing agent on compounds which are easily oxidized. During the reaction of mercaptanes, e.g. cysteine, homocysteine, cysteamine, with dansyl chloride, the corresponding disulfides are formed and dansyl chloride is reduced to 5-dimethylaminonaphthalene 1-sulfinic acid. This reaction is so rapid that the normal dansylation can take place only after complete oxidation of all SH-compounds. Therefore only the dansyl derivatives of the corresponding disulfides are formed during normal dansylation of SH-compounds. If different SH-compounds are present in the reaction mixture mixed disulfides are formed as well. These can be separated by microchromatography on 3 X 3 cm micropolyamide sheets. Dependent on the concentration of dansyl chloride, 6 or even 15 different dansylated disulfides are formed from three different SH-compounds so that interpretation of these chromatograms is difficult. The actual dansylmercaptanes (e.g., dansylcysteine, dansylhomocysteine, dansylcysteamine) can be prepared by reduction of the dansylated disulfides with suitable reducing agents.

Amino Acids↗
PubMed1979

A fluorometric method for the determination of praziquantel in blood-plasma and urine.

Some physicochemical data of praziquantel which may have analytical relevance are reported. For the quantitative determination praziquantel is extracted from plasma or urine by means of organic solvents and then hydrolyzed in an aqueous alkaline solution. The hydrolyzed product is reacted with dansyl-chloride (5-dimethylaminonaphthalene-sulfonylchloride). The dansylated compound is separated and quantified fluorometrically. The limit of determination is 3 micrograms/l in blood plasma and 30 micrograms/d in urine. For both fluids, the imprecision is approximately 7.5%. The method is suitable for the determination of praziquantel in patients or healthy volunteers treated with therapeutic doses.

Chemical Phenomena↗
PubMed1975

Fibrin-stabilizing factor inhibitors. 12. 5-Dibenzylaminopentylamine and related compounds, a new type of FSF inhibitors.

A series of omegadibenzylaminoalkylamines and related compounds have been prepared and tested as inhibitors of fibrin cross-linking. This structural type was chosen in an attempt to develop noncompetitive inhibitors of fibrinoligase. By the combination of the dibenzylamino moiety at one end and the primary amino group at the other end of a polymethylene chain, the same compound could function both as a pseudo donor substrate and as a noncompetitive alkylating inhibitor. Some of the compounds, notably 74-79, are among the most active fibrinoligase inhibitors described. However, the data indicate that the compounds probably function only as pseudo donor inhibitors.

Benzyl Compounds↗
PubMed1978

Sensitive fluorimetric method for the determination of putrescine, spermidine and spermine by high-performance liquid chromatography and its application to human blood.

A fast and sensitive method for the determination of putrescine, spermidine and spermine by high-performance liquid chromatography is described. These compounds are converted to their fluorescent dansyl derivatives and are separated by a reversed-phase chromatographic system (Micropak CH-10) with water and acetonitrile as mobile phase. The sensitivity of the method is 30 pmoles. The application of the method to the determination of polyamines in blood is described. It was found that most of the polyamines circulating in blood are localized in the erythrocytes, their content in normal human blood being spermidine 14.1 +/- 3.1, and spermine 8.4 +/- 2.8 nmoles/ml packed erythrocytes. The polyamine level in serum is less than 0.1 nmole/ml. The polyamine content of the erythrocytes from patients with malignant neoplasms was significantly elevated.

Chromatography, High Pressure Liquid↗
PubMed1975

Distribution of end-to-end distances of oligopeptides in solution as estimated by energy transfer.

A homologous series of oligopeptides each containing at its ends a donor and an acceptor of electronic excitation energy was synthesized by the solid-phase method. N-5-(2-Hydroxyethyl)-L-glutamine was the repeating unit, and peptides containing 4, 5, 6, 7, 8, and 9 of these amino-acid residues were prepared. The chromophores naphthalene and dansyl, which were used as donor and acceptor, respectively, fulfil the conditions necessary for energy transfer according to the Förster mechanism. A distance corresponding to 50% efficiency of energy transfer, tro = 22 plus or minus 1 A, was calculated. The kinetics of fluorescence decay of an oligomer containing the naphthalene chromophore only could be described precisely by a monoexponential function. In contrast, the kinetics of the decay curves of the fluorescence of the donor of all of the oligomers containing both donor and acceptor, as measured in viscous solution, deviated markedly from monoexponential behavior. The deviation was interpreted in terms of the great number of different conformations that the various molecules of each of the oligomers attain in solution, leading to characteristic end-to-end distribution functions between the donor and acceptor. Numerical adjustment of the parameters of some of the previously proposed expressions to describe the end-to-end distribution enabled the reconstruction of the kinetics of the fluorescence decay of the donor with great precision. The end-to-end distribution functions for the various oligopeptides were thus evaluated.

Alanine↗
PubMed1976

Influence of various fluorescent and non-fluorescent labels on the kinetics of the complex formation of alpha-chymotrypsin with basic pancreatic trypsin inhibitor (Kunitz).

The association of alpha-chymotrypsin with basic pancreatic trypsin inhibitor was studied using extrinsic signals produced by fluorescent and nonfluorescent labels. The reactive dyes were covalently bound to the proteins in the complexed state, in which the binding region was protected. The signals were sufficiently large to measure the complex formation at protein concentrations of 10(-9)M by fluorescence and down to 10(-6)M by absorption. Therefore, the association and dissociation could be followed over a broad range of concentration. Good correspondence was observed between data which were obtained with different labels and with published values for the unlabeled proteins. Existing differences could be explained by different buffer conditions used by the different authors. Also the pH dependence of the dissociation rate constants was essentially unaltered by the introduction of the labels. The large signals allowed a direct measurement of the equilibrium constants of dissociation, even at high pH, at which they are in the range of 10(-8)M. The experimentally determined binding constants were in agreement with those calculated from the rate constants. The temperature dependence of the binding constants revealed a small positive and pH-dependent enthalpy change [deltaHo = 4.0 kcal/mol (16.7 kJ) at H 7.0[. The results prove that the labeling can be performed in such a way that the equilibrium and kinetic parameters of the system studied are not significantly influenced.

Affinity Labels↗
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↗
PubMed1975

Denervation in the primary olfactory pathway of mice. II. Effects on carnosine and other amine compounds.

Carnosine (beta-alanyl-histidine) is present in the olfactory bulb and olfactory eqithelium of mice and rats at 1-2 nmole/mg tissue. Peripheral deafferentation or central denervation causes a rapid, selective decrease of this depeptide from the reciprocal portion of the primary olfactory pathway. These data demonstrate the localization of carnosine within the primary olfactory chemoreceptor neurons and suggest a possible role for this compound in neural transmission.

Alanine↗
PubMed1975

On the fluorimetric determination of oestriol in pregnancy urines after thin layer chromatography.

An improved method is described for the determination of oestriol concentrations in urines of pregnant women. Oestriol is detected as a derivate of 1-dimethylaminonaphtalene-5-sulphonylchloride (DANSYLchloride). The method has the following characteristics: 1. The recovery of oestriol-16-glucuronide is 94%. 2. For the interpretation of the results obtained with this method mean values and 95% probability bounds of urinary oestriol excretion for each week of the last three months of pregnancy are given. (e.g. 49--125 mumol/24 h at 32 weeks of gestation, 108--238 mumol/24 h at 40 weeks). 3. The coefficient of variation of the method is 4% (from day to day). 4. The lowest detectable concentration is 3 mumol/l. 5. Influence of glucose can be eliminated. 6. Other urinary compounds have no influence on the determination.

Birth Weight↗
PubMed1975

Quantitative thin-layer chromatography of pesticides.

Thus, it may be seen that quantitative TLC for pesticide residue analysis is still in an exploratory stage. Most work to date has been in method development with few actual field applications. At its best, quantitative TLC offers a viable alternative to gas chromatography or high speed liquid chromatography in terms of flexibility, cost, convenience and sensitivity. The availability of good instrumentation and sensitive methods of analysis for many compounds should lead to a wider acceptance and application of these techniques.

Carbamates↗
PubMed1977

Lysostaphin endopeptidase-catalysed transpeptidation reactions of the imino-transfer type.

The glycylglycine endopeptidase in lysostaphin has been found capable of catalysing both hydrolysis and transpeptidation reactions when acting on glycyl peptides. The ability of the enzyme to utilize dansyldiglycine (5-dimethylaminoaphthalene-1-sulphonylglycylglycine) as an acceptor molecule in transpeptidation reactions, although it is incapable of hydrolysing the peptide bond in this compound, indicates the enzyme must be capable of forming the equivalent of an imino-enzyme intermediate during the catalytic process.

Dansyl Compounds↗
PubMed1977

Energetics and molecular biology of active transport in bacterial membrane vesicles.

Bacterial membrane vesicles retain the same sidedness as the membrane in the intact cell and catalyze active transport of many solutes by a respiration-dependent mechanism that does not involve the generation of utilization of ATP or other high-energy phosphate compounds. In E. coli vesicles, most of these transport systems are coupled to an electrochemical gradient of protons (deltamuH+, interior negative and alkaline) generated primarily by the oxidation of D-lactate or reduced phenazine methosulfate via a membrane-bound respiratory chain. Oxygen or, under appropriate conditions, fumarate or nitrate can function as terminal electron acceptors, and the site at which deltamuH+ is generated is located before cytochrome b1 in the respiratory chain. Certain (N-dansyl)aminoalkyl-beta-D-galactopyranosides (Dns-gal) and N(2-nitro-4-azidophenyl)aminoalkyl 1-thio-beta-D-galactopyranosides (APG) are competitive inhibitors of lactose transport but are not transported themselves. Various fluorescence techniques, direct binding assays, and photoinactivation studies demonstrate that the great bulk of the lac carrier protein (ca. 95%) does not bind ligand in the absence of energy-coupling. Upon generation of a deltamuH+ (interior negative and alkaline), binding of Dns-gal and APG-dependent photoinactivation are observed. The data indicate that energy is coupled to the initial step in the transport process, and suggest that the lac carrier protein may be negatively charged.

Bacteria↗
PubMed1975

[Local anesthetic effect of several lipid-soluble compounds on the carbamylcholine response of the Electrophorus electroplax and the acetylcholine binding to the cholinergic receptor of Torpedo].

Several lipid soluble compounds: "Triton X-100", "Emulphogene BC-720" and 8-doxyl-palmitic acid behave-like local anesthetics on the in vivo response of Electrophorus electroplax to carbamylcholine and on the in vitro binding of 3-H acetylcholine to the membrane-bound cholinergic receptor from Torpedo.

Acetylcholine↗
PubMed1979

Determination of L-alanosine in plasma and urine by reversed-phase high-performance liquid chromatography of the Dns derivative.

L-Alanosine is an antitumour antibiotic that has recently been placed in clinical trial. We have developed a relatively rapid and specific assay for urinary and plasma alanosine, based on formation of the Dns derivative and separation of this from other Dns compounds by reversed-phase high-performance liquid chromatography. Dns-Alanosine is detected by its absorption at 254 nm, since alanosine is atypical in that it forms a Dns derivative with very low fluorescence. The lower limit of detection of alanosine in plasma is 0.1 microgram/ml. The assay has been used to measure the levels of alanosine in the plasma and urine of rabbits and of man.

Alanine↗
PubMed1979

S-(N-dansylaminoethyl)-6-mercaptoguanosine as a fluorescent probe for the uridine transport system in human erythrocytes.

A fluorescent derivative of 6-mercaptoguanosine, S-(N-dansylaminoethyl)-6-mercaptoguanosine, was synthesized, and found to be a strong inhibitor of the uridine transport system of erythrocyte (Ki approximately 0.3 microM). The emission spectrum of this compound has peaks at 400 and 550 nm. The emission at 550, but not that a 400 nm, in environment-sensitive. A method was devised for preparing a suspension of erythrocyte-membrane fragments with sufficiently low light scattering so that a detailed study could be made of the fluorescence of the probe when bound to membranes. Direct binding measurements showed the existence of a tight binding site, with a dissociation constant of the same order of magnitude as the inhibition constant. Binding of probe and substrate are not mutually exclusive, but the fluorescence and affinity of the bound probe are sensitive to the presence of uridine. The emission spectrum suggests that the bound probe penetrates into the bilayer region of the membrane.

Binding Sites↗