Structural investigations of the araban from guava, Psidium guajava L

1965 ◽  
Vol 18 (6) ◽  
pp. 851 ◽  
Author(s):  
UK Sengupta ◽  
AK Mukherjee ◽  
CVN Rao
Keyword(s):  
Light Scattering ◽  
Periodate Oxidation ◽  
Molecular Size ◽  
Psidium Guajava ◽  
Molar Ratio ◽  
Structural Investigations ◽  
Scattering Measurements ◽  
Degradation Studies ◽  
Hydrolysis Of

The pulp of guava, Psidium guajava L., contains an araban which can be enriched by extraction with 70% ethanol. Hydrolysis of the fully methylated pure araban, obtained during fractionation of the methylated polysaccharide, yielded 2,3,5-tri-, 2,3-di-, and 2-O-methyl-L-arabinofuranose in the molar ratio of 1 : 1.04 : 0.93, together with a small amount of arabinose. A structure has been suggested from these results which was corroborated by results from periodate oxidation studies. Sequence of branching has been confirmed from Barry degradation studies. Information about molecular size has been obtained from light scattering measurements.

STRUCTURE OF A GALACTURONAN FROM SUNFLOWER PECTIC ACID

1966 ◽  
Vol 44 (11) ◽  
pp. 1275-1282 ◽  
Author(s):  
V. Zitko ◽  
C. T. Bishop
Keyword(s):  
Galacturonic Acid ◽  
Periodate Oxidation ◽  
Degree Of Polymerization ◽  
Critical Assessment ◽  
Molar Ratio ◽  
Aqueous Methanol ◽  
Pectic Acid ◽  
Potassium Borohydride ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Fractions of sunflower pectic acid containing 89.8%, 94.2%, and 91.4% of D-galacturonic acid were carboxyl reduced as their methyl or ethylene glycol esters by potassium borohydride. Critical assessment of the effects of three different solvents (water, 80% aqueous dimethyl sulfoxide, and 80% aqueous methanol) on the efficiency of reduction showed that the latter solvent was best. The reductions caused a decrease in the degree of polymerization from 270 to 21. Measurement of the rates of hydrolysis of partially reduced pectic acids containing 90%, 41.6%, 19.9%, 11.0%, and 0.65% of D-galacturonic acid showed that the rate of hydrolysis was directly related to the proportion of galacturonosidic linkages present. Methylation and hydrolysis of the carboxyl-reduced pectic acid fractions yielded 2,3,4,6-tetra-O-methyl-D-galactose and 2,3,6-tri-O-methyl-D-galactose in an approximate molar ratio of 1:20. Results of the periodate oxidation of the carboxyl-reduced pectic acid supported the conclusion inferred from the methylation results that the pectic acid was a linear polymer of 1 → 4 linked α-D-galacturonic acid units.

CONSTITUTION OF A WATER SOLUBLE HEMICELLULOSE FROM AMERICAN BEECHWOOD (FAGUS GRANDIFOLIA)

1957 ◽  
Vol 35 (6) ◽  
pp. 556-564 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Average Molecular Weight ◽  
Periodate Oxidation ◽  
Reducing Power ◽  
Fagus Grandifolia ◽  
Water Soluble ◽  
Hot Water ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Homogeneous Fraction ◽  
Hydrolysis Of

Extraction of beechwood chlorite holocellulose with hot water yielded a hemicellulose in 13.4% yield (based on original extractive-free wood) containing D-xylose 72%, D-galactose 11.0%, and uronic acid 13.2%. Purification of the crude hemicellulose by complexing with Fehling's solution yielded a chemically homogeneous fraction containing D-xylose 83% and 4-O-methyl-D-glucuronic acid 15.5%. Hydrolysis of the fully methylated hemicellulose yielded 2,3,4-tri-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 3-O-methyl-D-xylose, and 3-O-methyl-2-O-(2,3,4-tri-O-methyl-D-glucopyranosyluronic acid)-D-xylose in a molar ratio of 2:35:3:5. On the basis of the methylation data, periodate oxidation, reducing power determinations, and weight average molecular weight values a possible structure for the hemicellulose is proposed.

Constitutron of the glucan from mango. Mangifera indica L. II. Barry degradation studies

1965 ◽  
Vol 18 (6) ◽  
pp. 845 ◽  
Author(s):  
A Das ◽  
CVN Rao
Keyword(s):  
Light Scattering ◽  
Mangifera Indica ◽  
Size And Shape ◽  
Scattering Measurements ◽  
Degradation Studies

From the results of Barry degradation studies, the 1→3 and 1→4 linked glucopyranose units present in the glucan have been proved to occur in blocks. Size and shape of the glucan have been determined from light-scattering measurements.

STRUCTURE OF AN ARABOGALACTAN FROM WHITE SPRUCE (PICEA GLAUCA (MOENCH) VOSS)

1958 ◽  
Vol 36 (5) ◽  
pp. 755-762 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Picea Glauca ◽  
Periodate Oxidation ◽  
White Spruce ◽  
Water Soluble ◽  
Molar Ratio ◽  
Glycosidic Bonds ◽  
Spruce Wood ◽  
Soluble Polysaccharide ◽  
Branched Structure ◽  
Hydrolysis Of

A water-soluble polysaccharide isolated from white spruce wood contained D-galactose, L-arabinose, and D-xylose in a molar ratio of 21:3:1. Hydrolysis of the fully methylated polysaccharide yielded 2,3,5-tri-O-methyl-L-arabinose (12 moles); 2,3,4,6-tetra-O-methyl-D-galactose (29 moles); 2,3,4-tri-O-methyl-D-galactose (34 moles); 2,6-di-O-methyl-D-galactose (0.5 moles); 2,4-di-O-methyl-D-galactose (45 moles); 2,3-di-O-methyl-D-xylose (5 moles); and monomethyl xylose (1 mole). When oxidized by periodate the polysaccharide consumed 1.18 moles of oxidant, and yielded 0.56 moles of formic acid per mole of anhydro-D-galactose. The D-xylose was attributed to the presence of a xylan mixed with the arabogalactan in the original polysaccharide preparation. The methylation and periodate oxidation data showed that the arabogalactan possessed a highly branched structure with the anhydro-D-galactose units being joined by 1 → 3 and 1 → 6 glycosidic bonds. All of the L-arabinose was present in the furanoside form as non-reducing terminal units.

STRUCTURAL STUDIES ON AN ARABINOXYLAN FROM PEA SKIN (PISUM SATIVUM): PART I. METHYLATION STUDIES

1963 ◽  
Vol 41 (11) ◽  
pp. 2844-2848 ◽  
Author(s):  
N. Banerji ◽  
C. V. N. Rao
Keyword(s):  
Pisum Sativum ◽  
Sodium Hydroxide ◽  
Sodium Hydroxide Solution ◽  
Periodate Oxidation ◽  
Structural Formula ◽  
Molar Ratio ◽  
Structural Studies ◽  
Hydroxide Solution ◽  
Hydrolysis Of

The polysaccharide extracted by 4% sodium hydroxide solution from pea skin (Pisum sativum) was shown to be composed of D-xylose and L-arabinose in a ratio of 5:1. Hydrolysis of the fully methylated arabinoxylan yielded 2,3,5-tri-O-methyl-L-arabinose, 2,3-di-O-methyl-D-xylose, and 2-O-methyl-D-xylose in the molar ratio of 1:4.2:1.1 and traces of 2,3,4-tri-O-methyl-D-xylose and D-xylose. From these results and those of periodate oxidation studies, a structural formula for the arabinoxylan has been proposed.

scholarly journals A study of the phosphate linkages in phosphomannan in cell walls of Saccharomyces cerevisiae

1972 ◽  
Vol 129 (3) ◽  
pp. 711-720 ◽  
Author(s):  
T. N. Cawley ◽  
M. G. Harrington ◽  
R. Letters
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Weight ◽  
Cell Walls ◽  
Periodate Oxidation ◽  
Deae Cellulose ◽  
Molecular Size ◽  
Molar Ratio ◽  
Alkaline Conditions ◽  
Phosphate Groups ◽  
Terminal Mannose

1. The phosphomannan of Saccharomyces cerevisiae was released by Pronase digestion of cell walls and isolated by chromatography on DEAE-cellulose or by precipitation with borate–Cetavlon solutions. Mannose and phosphorus were present in the molar ratio 18:1 and the phosphate groups were in the diester form. 2. Hydrolysis with acid gave mannose 6-phosphate. Under mild acid conditions (autohydrolysis) the phosphate groups were converted into the monoester form, mannose was released and the molecular size of the phosphomannan was substantially decreased. 3. Hydrolysis with alkali also gave a monoester phosphate and a similar decrease in molecular weight. Under mild alkaline conditions the serine and threonine content of the phosphomannan was decreased by about 80%. The phosphate content was not altered. 4. Treatment with 40% (v/v) HF removed 70% of the phosphorus from the phosphomannan with no detectable decrease in molecular weight. 5. Periodate oxidation gave an oxophosphomannan from which 80% of the phosphorus was eliminated under mild alkaline conditions. 6. The properties of the phosphomannan are consistent with a structure in which the phosphate groups are located on the outside of the molecule and link C-1 of a terminal mannose unit with C-6 of another mannose unit, which is in turn attached to the polysaccharide backbone of the molecule. 7. The implications of this structure are discussed in relation to flocculation.

scholarly journals MOLECULAR SIZE AND CONFIGURATION OF CELLULOSE TRINITRATE IN SOLUTION

1958 ◽  
Vol 36 (6) ◽  
pp. 952-969 ◽  
Author(s):  
M. M. Huque ◽  
D. A. I. Goring ◽  
S. G. Mason
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Ethyl Acetate ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Random Coil ◽  
Radius Of Gyration ◽  
Molecular Weight Range ◽  
Scattering Measurements ◽  
The Relationship

Viscosity and light-scattering measurements were made on several fractions and two unfractionated samples of cellulose trinitrate. The samples were prepared from bleached ramie, unbleached ramie, and cotton linters. The solvents were acetone and ethyl acetate. Viscosity was measured in a multishear viscometer designed for the purpose. Light-scattering measurements were made in a Brice-Phoenix Light-scattering Photometer modified to accommodate a cell which could be ultracentrifuged.The range of molecular weight investigated was from 6.5 × 105 to 25.0 × 105 The relationship between the z-average mean-square radius of gyration, [Formula: see text] and the z-average molecular weight was approximately linear in both solvents. The ratio of [Formula: see text] (where [Formula: see text] is the value of [Formula: see text] in the unperturbed state) was found constant in acetone but to increase with [Formula: see text] in ethyl acetate. This indicated that, whereas in acetone random coil configuration was attained, a configurational transition occurred in ethyl acetate in the molecular weight range investigated.The value of the exponent a in the relationship between intrinsic viscosity and molecular weight was found to be lower than unity but approximately equal in both solvents.The significance of the experimental data is discussed.

CONSTITUTION OF THE GALACTOMANNAN FROM THE KERNEL OF GREEN PALMYRA PALM NUT (BORASSUS FLABELLIFER LINN.)

1961 ◽  
Vol 39 (7) ◽  
pp. 1408-1418 ◽  
Author(s):  
A. K. Mukherjee ◽  
D. Choudhury ◽  
P. Bagchi
Keyword(s):  
Periodate Oxidation ◽  
Structural Formula ◽  
Water Soluble ◽  
Molar Ratio ◽  
Partial Hydrolysis ◽  
Soluble Polysaccharide ◽  
Hydrolysis Of

The water-soluble polysaccharide extracted from the kernel of green palmyra palm nut (Borassusflabellifer Linn.) was shown to be composed of D-galactose and D-mannose in the proportion of 1:2.4. Hydrolysis of the fully methylated galactomannan yielded 2,3,4,6-tetra-O-methyl-D-galactose, 2,3,6-tri-O-methyl-D-mannose, and 2,3-di-O-methyl-D-mannose in the molar ratio of 1:1.4:0.95. Partial hydrolysis of the galactomannan afforded 4-O-β-D-mannopyranosyl-D-mannose, 6-O-α-D-galactopyranosyl-D-mannose, and two trisaccharides. Based on these results a structural formula for the galactomannan has been proposed, additional evidence for which was adduced from periodate-oxidation studies.

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