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Biomedical subjects

R J Sturgeon

Publications and source records attributed to R J Sturgeon.

At least 19 recordsLinked to original sources
PubMed1982

Affinity chromatography of sialoglycoproteins, utilising the interaction of serotonin with n-acetylneuraminic acid and its derivatives.

Serotonin, immobilised on Sepharose 4B, has been used to study the affinity chromatography of neuraminic acid and its derivatives. Free N-acetylneuraminic acid and oligosaccharides, polysaccharides, and glycoproteins containing that sugar are specifically bound to the columns. Removal of neuraminic acid from sialoglycoconjugates, or modification of the neuraminic acid residues by periodate oxidation, abolishes their ability to bind to the ligand. The presence of the N-acetyl group, but not the N-glycolyl group, and the integrity of the side chain (C-7-C-9) of the neuraminic acid are essential for binding to serotonin.

Acid Phosphatase↗
PubMed1980

Titratable acidities of crystalline amino acid admixtures.

Titration curves for total parenteral nutrient (TPN) products were developed and used to determine the amount of alkali needed to make various pH changes. Equations and graphs for determining the titratable acidities of TPN solutions are presented. Samples of five crystalline amino acid products and of 1:1 mixtures of the products with 50% dextrose solutions were titrated to pH 7.4 (with a standard sodium bicarbonate solution) or 8.0 (with a standard sodium hydroxide solution). The samples titrated with sodium hydroxide were first adjusted to pH 5.0 with hydrochloric acid. The pH of the sample was measured after each 0.1-ml addition of hydroxide or bicarbonate to develop a titration curve. Titratable acidities for the five crystalline amino acid products varied widely, ranging from 13.4--45.2 meq of hydroxide/liter and from 135--420 meq of bicarbonate/liter. The amino acid/dextrose mixtures had titratable acidities ranging from 7.8--24.8 meq of hydroxide/liter and from 87--226 meq of bicarbonate/liter. The pH titration data can be used as a guide for determining the amount of base to add to TPN solutions to obtain the desired pH.

Amino Acids↗
PubMed1979

Improved spectrophotometric determination of glycerol and its comparison with an enzymatic method.

A chemical method for the determination of glycerol was developed and compared to an enzymatic assay for sensitivity and reproducibility. The chemical assay is based on glycerol oxidation to formaldehyde and subsequent reaction with chromotropic acid to yield a colored product. With this method, as little as 5 micrograms of glycerol/ml can be detected. The enzymatic assay is based on enzymatic glycerol phosphorylation followed by glycerol phosphate dehydrogenation by nadide (nicotinamide adenine dinucleotide). The reduced nadide is used to reduce iodonitrotetrazolium violet to its colored formazan product. The enzymatic method can be used to deterine 50 micrograms of glycerol/ml in aqueous samples.

Glycerol↗
PubMed1978

Spectroscopic approach to estimation of microequilibrium constants of prototropic reactions of aminobenzoic acids.

The microequilibrium constants of protolytic dissociation of diprotic acids, dihydric bases, or ampholytes such as the aminobenzoic acids, with dissimilar ionizing groups, can be estimated by spectrophotometric titration and measurement of the molar absorptivity at the long wavelength absorption maximum of simple alkylated derivatives. The method is applicable when the long wavelength absorption spectral bands of the tautomeric species are well resolved. Compared to the traditional method of estimating microequilibrium constants using the dissociation constants of alkylated derivatives, the proposed method is simpler, faster, and more accurate.

Aminobenzoates↗
PubMed1977

Electronic absorption spectra and protolytic equilibria of doxorubicin: direct spectrophotometric determination of microconstants.

The ground- and excited-state dissociation constants and the electronic absorption and fluorescence spectra of doxorubicin were investigated by spectrophotometry. A general method for the direct calculation of individual microscopic dissociation constants was derived using the spectrophotometric data obtained. It was concluded that the protonated amino sugar group is slightly more acidic than the phenolic group. The spectrophotometric data were analyzed, and the macro- and microconstants for the various equilibria was reported.

Chemical Phenomena↗
PubMed1977

In vitro adsorption of doxorubicin hydrochloride on insoluble calcium phosphate.

The adsorption of doxorubicin hydrochloride, a potent antitumor agent, on solid tribasic calcium phosphate was studied in vitro. A Langmuir adsorption isotherm at pH 7.4 and the maximum adsorption capacity of tribasic calcium phosphate were established. Tribasic calcium phosphate was chosen as a model for solid bone samples, which are stained with doxorubicin in patients who have received long-term doxorubicin therapy.

Adsorption↗
PubMed1977

Binding of N-substituted anthracenecarboxamides to double-stranded DNA: an electronic spectral study.

The electronic absorption and fluorescence spectra of two isomeric anthracenecarboxamides substituted with quaternary alkyl ammonium groups were studied as a function of solvent polarity, solvent rigidity, and state of protonation. These relatively simple environmental perturbations of the electronic spectra were employed to interpret spectral shifts caused by complexation with the bases or base pairs of DNA. The exocyclic side chains of the compounds studied have some freedom of movement when the spectroscopic probes are bound to double-stranded DNA.

Anthracenes↗
PubMed1977

Purification of some glycoside hydrolases by affinity chromatography.

Two glycoproteins have been isolated from the cell walls of baker's yeast. One is a glucan-protein complex which has been partially characterised as having a branched carbohydrate structure composed of chains of (1 leads to 3)-linked beta-D-glucosyl residues, some of which are attached by (1 leads to 6)-linkages to the main chain. Immobilization of this glycoprotein was achieved by covalent attachment to Sepharose, and the product was used to isolate a number of (1 leads to 3)-beta-D-glucan hydrolases from Helix pomatia, malted barley, and Basidiomycete QM806. The second glycoprotein, a mannan-protein complex, after immobilization, has been used in the purification of an alpha-D-mannosidase from jack-bean meal.

Acetylglucosaminidase↗
PubMed1976

Steric inhibition of conjugation in lowest excited singlet state of 9-anthramide by hydrogen bond donor solvents: role of solvent in chemical structure.

9-Anthramide has electronic absorption and fluorescence spectra that, in water, are similar to those of anthracene. This result is attributed to steric hindrance of the 9-carboxamido group with the peri-hydrogen atoms in the 1- and 8-positions of the anthracene ring. However, in aprotic solvents, although the absorption spectrum of 9-anthramide is anthracene-like, its fluorescence spectrum is red shifted and structureless. This finding is attributed to excited-state rotation of the 9-carboxamido group into coplanarity with the anthracene ring and indicates that, in water, the hydrogen-bonded solvent cage affects the steric inhibition of conjugation in excited 9-anthramide. These findings suggest that studies of structure and reactivity of drugs in nonaqueous or solid matrixes are probably of only limited value, since in the strongly interacting aqueous media the aqueous solvent cage plays a substantial role in determining molecular structure and reactivity.

Amides↗
PubMed1976

The oxidation of terminal D-galactofuranose residues of a galactan and a glycoprotein by a D-galactose oxidase preparation from Dactylium dendroides.

A galactan, isolated from the unicellular organism Prototheca zopfii, and a glycoprotein from a hyphal cell-wall fraction of the fungus Pithomyces chartarum have been oxidised by a D-galactose oxidase preparation from Dactylium dendroides. The oxidised polymers were subsequently reduced with sodium borotritide. The site of oxidation was identified as C-6 of non-reducing D-galactofuranosyl residues in both polymers.

Alcohol Oxidoreductases↗