Changes in the hemicellulosic polysaccharides of Avena coleoptile cell walls during growth of intact seedlings

1988 ◽  
Vol 66 (5) ◽  
pp. 949-954 ◽  
Author(s):  
M. Teresa Herrera ◽  
Ignacio Zarra
Keyword(s):  
Molecular Weight ◽  
Avena Sativa ◽  
Cell Walls ◽  
Average Molecular Weight ◽  
Relative Content ◽  
The Other ◽  
Polysaccharide Fraction ◽  
Avena Coleoptile ◽  
Main Component ◽  
Soluble Part

The variations taking place in the major polysaccharides of the cell wall of Avena sativa L. cv. Victory coleoptiles were studied during growth. Two fractions were obtained, one corresponding to cellulose and the other to the hemicelluloses. The relative content of cellulose was greater in the basal regions of the coleoptiles and the proportion of this polysaccharide fraction increased in all regions during growth. The hemicellulosic fraction was composed of two parts, an insoluble one designated the HC A hemicellulosic fraction, whose main component was seen to be an insoluble xyloglucan, and a soluble part designated the HC B hemicellulosic fraction, composed of an arabinoxylan and a (β1-3)- or (β1-4)-glucan. This latter was degraded during the growth of the coleoptiles. The average molecular weight of hemicelluloses HC A and HC B decreased from the sub-apical zones to the basal zones of the coleoptiles; this was related to the growth capacity of each of the regions into which the coleoptiles were divided.

scholarly journals The Molecular Weight At the Air-Water Interface of Some Keratin Derivatives Extracted From Wool

1955 ◽  
Vol 8 (1) ◽  
pp. 122 ◽  
Author(s):  
BS Harrap
Keyword(s):  
Molecular Weight ◽  
Cell Walls ◽  
Average Molecular Weight ◽  
Cortical Cell ◽  
Number Average Molecular Weight ◽  
Molecular Weights ◽  
Reversible Dissociation ◽  
Electrophoretic Patterns ◽  
Air Water Interface ◽  
Electrophoretic Component

Using the monolayer technique, number-average molecular weights have been determined for a series of extracts of wool prepared by successive treatments with alkaline sodium thioglycollate. The molecular weights of these extracts have been discussed in relation to their electrophoretic patterns. The change in the number-average molecular weight in the successive extracts has been correlated with the presence of certain electrophoretic components. The possibility of extraction of lipoidal or other non-protein material from the cortical cell walls is discussed. A reversible dissociation of the major electrophoretic component at high pH was observed.

scholarly journals Studies on the Uncrosslinked Fraction of PLA/PBAT Blends Modified by Electron Radiation

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1068 ◽  
Author(s):  
Rafał Malinowski ◽  
Krzysztof Moraczewski ◽  
Aneta Raszkowska-Kaczor
Keyword(s):  
Molecular Weight ◽  
Fourier Transform ◽  
Thermal Properties ◽  
Infrared Spectroscopy ◽  
Quantitative Analysis ◽  
Average Molecular Weight ◽  
The Other ◽  
Electron Radiation ◽  
Different Molecular Weight

The results of studies on the uncrosslinked fraction of blends of polylactide and poly(butylene adipate-co-terephthalate) (PLA/PBAT) are presented. The blends were crosslinked by using the electron radiation and triallyl isocyanurate (TAIC) at a concentration of 3 wt %. Two kinds of samples to be investigated were prepared: one contained 80 wt % PLA and the other contained 80 wt % PBAT. Both blends were irradiated with the doses of 10, 40, or 90 kGy. The uncrosslinked fraction was separated from the crosslinked one. When dried, they were subjected to quantitative analysis, Fourier transform infrared spectroscopy (FTIR) measurements, an analysis of variations in the average molecular weight, and the determination of thermal properties. It was found that the electron radiation caused various effects in the studied samples, which depended on the magnitude of the radiation dose and the weight fractions of the components of the particular blends. This was evidenced by the occurrence of the uncrosslinked fractions of different amounts, a different molecular weight distribution, and the different thermal properties of the samples. It was also concluded that the observed effects were caused by the fact that the processes of crosslinking and degradation took place mostly in PLA, while PBAT appeared to be less susceptible to the influence of the electron radiation.

Unsaturation of Polyisobutylenes and Butyl Rubber. Reactions with Nitrosobenzene, Thiocyanogen, Iodine Monochloride, and Ozone

1944 ◽  
Vol 17 (3) ◽  
pp. 679-692 ◽  
Author(s):  
John Rehner
Keyword(s):  
Molecular Weight ◽  
Small Molecules ◽  
Extreme Values ◽  
Average Molecular Weight ◽  
The Other ◽  
Iodine Monochloride ◽  
Incomplete Reaction ◽  
A Current ◽  
End Group ◽  
Good Agreement

Abstract Table III summarizes unsaturation values obtained for the various polymers. The ranges indicated are, in most cases, extreme values of determinations made with two or more different samples of a given polymer type. Taking into consideration the small amounts of unsaturation involved, the values based on end-group determinations are in reasonably good agreement with one another and with the values based on the viscosity of the degraded polymer. Higher values are observed for the nitrosobenzene determinations, but these are considered to be less reliable because of the ease with which oxidation phenomena can occur with this reagent. The thiocyanogen values are the lowest of all; on the basis of values obtained by the other methods as well as of experimental evidence not included in this paper, these values are believed to result from incomplete reaction. As a class the iodine monochloride methods give considerably higher values than those obtained with the other reagents. This may be attributed to the substitution reaction that readily occurs with that reagent. The effect is perhaps most marked in the data obtained for polyisobutylene sample 2 with 0.1 N Wijs reagent; the upper value (0.4) is far greater than can be explained on the basis of the knowa molecular weight of this polymer and the corresponding terminal double bond contribution. Furthermore, since this polymer sample was fractionated in such a way as to remove all species of viscosity-average molecular weight less than about 50,000, the high value cannot be ascribed to the presence of dimers, trimers, or other small molecules formed during polymerization. In view of the data and the above considerations, it is believed that the unsaturation values based on ozone degradation are correct within the limits of experimental error, and that this reagent makes possible a relatively good estimation of the number of double bonds in polymers such as have been described. A modified procedure more suitable for rapid evaluations is the object of a current investigation.

The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

1971 ◽  
Vol 29 ◽  
pp. 76-77
Author(s):  
C. E. Cluthe ◽  
G. G. Cocks
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Parallel Plate ◽  
Average Molecular Weight ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Nitrogen Gas ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

The Kidney and Fibrinolysis

1970 ◽  
Vol 24 (01/02) ◽  
pp. 026-032 ◽  
Author(s):  
N. A Marsh
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Enzyme System ◽  
Normal Animal ◽  
Fibrinolytic Enzyme ◽  
The Other ◽  
Exclusion Chromatography ◽  
Normal Urine ◽  
Renal Origin ◽  
Molecular Exclusion Chromatography

SummaryMolecular exclusion chromatography was performed on samples of urine from normal and aminonucleoside nephrotic rats. Normal urine contained 2 peaks of urokinase activity, one having a molecular weight of 22,000 and the other around 200,000. Nephrotic urine contained three peaks of activity with MW’s 126,000, 60,000 and 30,000. Plasma activator determined from euglobulin precipitate had a MW. in excess of 200,000. The results indicate that in the normal animal, plasma plasminogen activator does not escape into the urine in substantial quantities but under the conditions of extreme proteinuria there may be some loss through the kidney. The alteration in urokinase output in nephrotic animals indicates a greatly disordered renal fibrinolytic enzyme system.The findings of this study largely support the hypothesis that plasma plasminogen activator of renal origin and urinary plasminogen activator (urokinase) are different molecular species.

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

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