E.J. Bourne

Studies on dextrans and dextranases : Part X. Types and percentages of secondary linkages in the dextrans elaborated by leuconostoc mesenteroides NRRL B-1299

Abstract The water-soluble (dextran S) and less water-soluble (dextran L) dextrans elaborated by Leuconostoc mesenteroides NRRL B-1299 contain α- d -glucopyranose residues linked through positions 1 and 6, 1 and 3, as well as 1, 2, and 6. The approximate number of terminal non-reducing d -glucose residues and those linked through positions 1 and 6, 1 and 3, as well as 1, 2, and 6 in the average repeating-unit of dextran S are 5, 4, 1, and 5. The corresponding figures for dextran L are 5, 4, 3, and 5.

Carbohydrates of acetabularia species : Part I. A. crenulata

Abstract The green seaweed Acetabularia crenulata is shown to synthesise d -glucose, fructose, sucrose, ribo-hexulose, myo-inositol and a second alcohol (tentatively identified as allo-quercitol), aqueous alcohol-soluble inulin-type oligosaccharides, a water-soluble inulin-type polysaccharide, and a complex acid-containing polymer. Alkali extracts a polydisperse mannan which has an average chain-length of ∼14, β-(1→4)-linked d -mannose residues, and some degree of branching.

Complexes between polyhydroxy compounds and copper(II) ions

Abstract Several polyhydroxy compounds have been shown to form cationic complexes with copper(II) ions. Paper electrophoresis in copper(II) acetate and basic co

Studies on dextrans and dextranases : Part XI. The structure of a dextran elaborated by Leuconostoc mesenteroides NRRL B-1299

Abstract In dextran S elaborated by Leuconostoc mesenteroides NRRL B-1299, the polymeric chain consists, principally, of segments of isomaltose homologues which are mutually linked through positions 1 and 2 of their terminal D -glucose residues. The average repeating-unit, containing a total of fifteen D -glucose residues, possesses five branches which occur at each position 6 of such segments and at positions 2. Branches consist mainly of α- D -glucopyranosyl groups and some appear to be terminated by α-nigerosyl groups.

The active carbohydrate metabolites of the brown seaweed, Fucus vesiculosis

Abstract Biosynthetic studies with Na 2 14 CO 3 on Fucus vesiculosus by Bidwell 2 have shown that d -mannitol is the main respiratory substrate, but that a proportion of the radioactivity is incorporated into fucoidin, alginic acid, alkali-soluble alcohol-soluble material, and into the insoluble residue remaining after the removal of the other materials by acid and alkali extraction. The quantity of seaweed used in the biosynthetic studies prevented a complete investigation of the various materials. Large-scale extraction, under the conditions used in the above studies, has now revealed that the “fucoidin” is indeed a mixture of fucoidin and laminarin, and that the “alginic acid” is contaminated with a sulphated glucuronoxylofucan which has been found in this genus for the first time. The alkali-soluble, alcohol-soluble material is a partially degraded portion of this glucuronoxylofucan. Further extraction of the insoluble residue gives additional, crude glucuronoxylofucan, and an acid-insoluble and an acid-soluble glucan are separated by extraction with 6 n alkali after mild treatment with chloride. Tentative evidence is advanced for the presence of (1 → 3)- and (1 → 4)-linked d -glucose units in these glucans and in the final residue.

A detailed investigation of the acid-catalysed formation of acetals from acetone and D-glucitol

Abstract The acid-catalysed acetonation of D -glucitol has been studied in detail. The true complexity of the reaction, giving the 1,2- and 3,4-monoacetals, the 1,2:3,4-, 3,4:5,6-, and 1,2:5,6-diacetals, and the 1,2:3,4:5,6-triacetal, has been shown. These studies have been carried out mainly by gas-liquid chromatographic techniques, and have shown that, with acetone, the primary hydroxyl group at C-1 is more reactive than that at C-6. The structures of the various acetals have been verified by p.m.r. spectroscopy.

The structure of the benzeneboronate of pentane-1,3,5-triol

Abstract The relative ease of formation of five-, six-, seven-, and eight-membered cyclic benzeneboronates is discussed. Pentane-1,3,5-triol forms, by interaction with benzene-boronic anhydride, exclusively DL -4-(2-hydroxyethyl)-2-phenyl-1,3,2-dioxaborinane. It is suggested that, in this compound, the oxygen atom of the hydroxyl group is intramolecularly co-ordinated with the boron atom.

Butylidene acetals of galactitol

Abstract The acid-catalysed reaction of galactitol with butyraldehyde yields the 1,3- and 2,3-mono- and 1,3:4,6-di-acetals, the structures of which were proved by chemical methods. The separation of acetals on an anion-exchange resin is described. Mass spectrometry and n.m.r. spectroscopy were used for characterisation of the methylated acetals and certain partially methylated derivatives of galactitol derived therefrom.

2,4:3,5-di-O-benzylidene-D-glucitol

Abstract Chemical proof is given that the acetal groups in the known 2,3,4,5-di- O -benzylidene- D -glucitol span the 2,4- and 3,5-positions.

Studies on tert-butyl derivatives of D-glucose

Abstract tert -Butyl α- and β- D -glucopyranoside have been shown to adopt the C1 conformation. Treatment of D -glucose with tert -butyl alcohol, in the presence of an acid catalyst, yields 6- O - tert -butyl-β- D -glucopyranose and a small proportion of 2- O-tert -butyl- D -glucose.