Katura Tuzimura

Proton magnetic resonance spectra of D-gluco-oligosaccharides and D-glucans

Abstract The p.m.r. spectra of some D -gluco-oligosaccharides and D -glucans in deuterium oxide were studied with respect to the anomeric proton. In (1→2)-linked glucobioses, the effect of change in configuration of the hydroxyl group at C-1 on the chemical shifts of the glycosidic proton is noted. Equilibrium mixtures of (1→2)-linked glucobioses contained more α-anomer than did the other examples, despite the cis configuration of substituents at C-1 and C-2. Some D -glucans were investigated with regard to the degree of branching, although solubility was a limitation.

A critical study of the measurement and calibration of circular dichroism.

Abstract A critical study has been made of circular dichroism (CD) measurements at the wavelengths around 500, 290, and 220 nm. Instruments calibrated at 290 nm with (+)-camphor-10-sulfonic acid gave results for molecular ellipticities [θ] showing deviations up to >30%, at both 220 and 490 nm. Older instruments tended to given higher values of [θ] at 490 nm and lower values at 220 nm, probably due to the age of the Pockel cells. A proposal is made to use d -pantolactone and (+)-tris(ethylenediamine) cobalt (III) iodide monohydrate as calibration standards at 220 and 490 nm, respectively, together with (+)-camphor-10-sulfonic acid at 290 nm.

d-Pantolactone as a circular dichromism (CD) calibration

Abstract A critical study of circular dichromism (CD) measurement at the wavelength region around 220 nm was made. Test sample methods gave deviations of abou 20%, at most, between instruments calibrated at 290 nm with D-10-camphorsulfonic acid. A calculation of the CD from optical rotatory dispersion (ORD) data was made for d -pantolactone which gave a CD maximum at 219 nm, [ θ ] 219 25 = −17.3 × 10 3 in water. A proposal is made to use this value for calibration of CD in the 220-nm region.

13 C nuclear magnetic resonance spectra of glucobioses, glucotrioses, and glucans

Natural-abundance carbon-13 n.m.r. spectra of all the glucobioses and of four selected glucotrioses in aqueous solution have been measured and are discussed. Peak assignments were made on the basis of comparison with the spectra of methyl glucopyranosides, four mono-O-methylglucoses and five methyl glucobiosides. Carbon-13 n.m.r. spectroscopy proved to be a useful tool for stereochemical characterisation of these oligosaccharides. In addition, carbon-13 n.m.r. spectra of the β-limit dextrins from glycogen and amylopectin have been measured and the differences between them are discussed.

Thin-layer chromatography of amino acid hydantoins☆

Amino acid hydantoins were detected directly in amounts of 0.2–0.5 μg with tert.-butyl hypochlorite. The amino acid hydantoins were separated by thin-layer chromatography using the following solvent systems: (I) chloroform-ethanol-formic acid (2:1:1); (II) n-butyl acetate-ethanol-formic acid (12:2:1); (III) dichloroethane-ethanol-formic acid (80:20:1); and (IV) n-butanol-acetic acid-water (15:2:5). The terminal amino groups of several proteins were detected successfully.

Reaction of Fluorescein-isothiocyanate with Proteins and Amino Acids: Part III. Syntheses of Trifluoroacetic Acid Salts of Fluorescein-thiohydantoin Amino Acids and their Spectrometric Studies

The structure of fluorescein chromophore was studied with infrared and nuclear magnetic resonance spectrometries. Fluorescein chromophore formed acid salt with strong acid and this salt was decomposed with water.Fluorescein derivatives were allowed to crystallize into trifluoroacetic acid salts. The new compounds, trifluoroacetic acid salts of fluorescein thiohydantoin (FTH)* amino acids, were synthesized and they were studied with ultraviolet, visible, fluorescence and infrared spectrometries, as well as optical rotatory dispersion and nuclear magnetic resonance.The trifluoroacetic acid salts of FTH-amino acids were superior to trifluoroacetic acid-free form as the standard materials of N-terminal analysis.