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At least 847 records · Page 47Linked to original sources
PubMed1988

Resolution of the intermediates of de novo purine biosynthesis by ion-pair reversed-phase high-performance liquid chromatography.

An ion-pair reversed-phase high-performance liquid chromotographic procedure capable of resolving twelve of the fourteen intermediates of de novo purine biosynthesis is presented. The method utilizes isocratic elution and detection by ultraviolet light absorption. Separation of all twelve intermediates can be achieved in 90 min.

Chromatography, High Pressure Liquid↗
PubMed1981

Analysis of chromosome movement in crane fly spermatocytes by ultraviolet microbeam irradiation of individual chromosomal spindle fibres. II. Action spectra for stopping chromosome movement and for blocking ciliary beating and myofibril contractions.

Chromosome-to-pole movement in crane fly spermatocytes was temporarily blocked by ultraviolet light focussed to a 4-micrometer-diameter spot on single chromosomal spindle fibres. Since similar irradiation of the interzonal region did not alter chromosome-to-pole movement, this effect was specific to spindle fibres. The action spectrum for blocking chromosome movement in this specific way had two peaks, one at 270 nm and one at 290 nm. To block movement, irradiations with 280-nm-wavelength light required two to four times more energy than irradiations with 270- or 290-nm-wavelength light. Action spectra were obtained for blocking ciliary beating and for blocking myofibril contraction. The action spectrum for blocking ciliary beating had a broad peak, between 260 nm and 280 nm, whilst that for blocking myofibril contraction had two peaks, at 270 and 290 nm, just like that for blocking chromosome movement. We discuss the similarities and differences in the various action spectra, and we compare the action spectra to absorption spectra of spindle components and to other action spectra (e.g., that for depolymerizing actin-containing filaments). Absorption spectra were obtained for ultraviolet light passing through spindle fibres as well as for ultraviolet light passing through the interzone.

Animals↗
PubMed2000

Comparison of three methods to determine the whey protein to total protein ratio in milk.

Three methods for quantification of the ratio of whey protein in total protein [capillary electrophoresis (CE), sodium dodecyl sulfate capillary electrophoresis (SDS-CE), and UV fourth derivative absorption spectroscopy (UV-4th Der.)] were applied to raw (n = 21), pasteurized (n = 5) and UHT (n = 18) milk samples. All methods effectively measured the whey protein to total protein ratio independently of the heat treatment applied to the milk. Mean values obtained by CE, SDS-CE and UV-4th Der. were respectively, 17.1, 18.5, and 17.2% for raw milks, 16.6, 17.7, and 18.8% for pasteurized milks, and 16.8, 17.0, and 17.2% for UHT milks. (Key words: whey protein to total milk protein ratio, capillary electrophoresis, sodium dodecyl sulfate capillary electrophoresis, fourth derivative ultraviolet spectroscopy)

Animals↗
PubMed2001

[Synthesis and ultraviolet-visible spectrum of two new symmetrical porphyrins].

Meso-tetra(p-benzoylaminophenyl) porphyrin or meso-tetra (o-benzoylaminophenyl) porphyrin are synthesized by condensation of meso-tetra (p-aminophenyl) porphyrin or meso-tetra (o-aminophenyl) porphyrin and benzoyl chloride in DMF using NaOH as catalyst, these porphyrins and the method have not been reported previously. Their structures are ascertained by elemental analysis, ultraviolet-visible spectrum, IR and 1H-NMR measurements. The ultraviolet-visible spectrum of the two porphyrins is discussed in detail.

Molecular Structure↗
PubMed1986

[Use of spectral methods in the study of poisoning].

The authors demonstrate on selected cases from routine practice the possibility of rational and effective use of spectral methods in the examination of intoxications. They discuss the use of ultraviolet and infrared spectroscopy, in particular their combination with chromatographic methods (chromatography on a thin layer, gas chromatography).

Acetaminophen↗
PubMed1984

[A method for determination of prostaglandins in human seminal fluid].

Human seminal fluid has been shown to contain mainly eleven different prostaglandins. Methods for quantitative determination of prostaglandin E and 19-OH prostaglandin E are described. The methods include extraction with acetone and alkali treatment. After alkali treatment prostaglandin E was transformed to prostaglandin B, and 19-OH prostaglandin E to 19-OH prostaglandin B. Prostaglandins were separated by using Lipidex column chromatography and silicic acid column chromatography. Prostaglandin B was quantitated by gas chromatography using C24 fatty acid methyl ester as internal standard. 19-OH prostaglandin B was quantitated by measuring ultraviolet photoabsorbance at 278 nm.

Alprostadil↗
PubMed1997

In vitro evidence for UV-protection of the eye by the corneal epithelium mediated by the cytoplasmic protein, RNA, and ascorbate.

PURPOSE: (1) To evaluate the effect of ribonucleic acid (RNA) and ascorbate on UV-absorption and their impact on ultraviolet-induced (UV) fluorescence from various proteins, and (2) to compare RNA and DNA reduction of protein fluorescence. These informations will be useful for later work on the UV-filtering effect of the corneal epithelium. METHOD: Spectrophotometry and spectrofluorimetry. RESULTS: (1) RNA and ascorbate caused a significant UV-absorption and reduced the fluorescence from various water-soluble proteins, the degree of reduction varying independently from one protein to the other. (2) RNA and DNA showed protein fluorescence reduction of roughly the same order. CONCLUSION: The results are discussed both in the context of UV-protection of the cell nucleus in general, and the possible UV-filtering effect for the eye of bovine corneal epithelium.

Animals↗