scholarly journals Molecular-mass distribution of tundra soils humic substances from the European northeast of Russia

2015 ◽  
Author(s):  
Roman Vasilevitch ◽  
Evgeniy Lodygin ◽  
Vasiliy Beznosikov
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Mass Distribution ◽  
Weight Fraction ◽  
Fulvic Acids ◽  
Low Molecular Weight ◽  
Tundra Soils ◽  
Molecular Weight Fractions ◽  
Different Molecular Weight ◽  
A Share

It is established that the humic acids (HA) of tundra soils contain three fractions with a different molecular weight: ≥600, 62–83 and 2,6–5,3 kDa; fulvic acids (FA) — one fraction — 1,5–4,4 kDa. The maintenance of a low molecular weight fraction of HA considerably exceeds a share of medium and high molecular weight fractions. Reclamation of tundra surface-gley soils leads to decrease of a share of high molecular weight and to increase of a share of low molecular weight fraction as a part of HA. Correlative dependences between the contents of HA molecular weight fractions with parameters of HA are established. Refs 16. Figs 1. Tables 3.

STRUCTURE AND CHEMICAL CONTENTS OF MUCILAGE CELLS IN PSEUDOLARIX AND ABIES BARK

IAWA Journal ◽  
2015 ◽  
Vol 36 (3) ◽  
pp. 300-310
Author(s):  
Fengping Jia ◽  
Jiayan Luo ◽  
Ryosuke Takahashi ◽  
Chie Uehira ◽  
Shinichi Kitamura ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Average Length ◽  
Weight Fraction ◽  
Ruthenium Red ◽  
Low Molecular Weight ◽  
High Molecular Weight Fraction ◽  
H Nmr ◽  
Molecular Weight Fractions ◽  
Chemical Contents

Mucilage is extruded from the bark of Pseudolarix amabilis and Abies nephrolepis upon injury. The aim of this study was to characterize the structure and chemical contents of mucilage extruded from mucilage cells (MCs) in the bark of these species. A large number of MCs containing translucent or dark materials in their lumina were observed in the secondary phloem of P. amabilis and A. nephrolepis. The translucent or dark materials in MCs stained positive with ruthenium red and PAS, indicating the presence of polysaccharides. The average length and diameter of MC in P. amabilis were 1500 μm and 254 μm, respectively, and the corresponding values for A. nephrolepis were 419 μm and 166 μm. Chemical analysis of low molecular weight fractions prepared from mucilage by HPAEC-PAD showed sucrose, glucose and fructose peaks, and in addition galacturonic acid and fucose peaks. Furthermore, 1H NMR spectra for the high molecular weight fraction showed the signals characteristic of pectin. This demonstrates that the mucilage consists mainly of low molecular weight carbohydrates and high molecular weight polysaccharide pectin.

Some Osmotic Measurements of the Molecular Weight of a High Molecular-Weight Fraction of Rubber Hydrocarbon

1955 ◽  
Vol 28 (2) ◽  
pp. 504-507
Author(s):  
G. W. Drake
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Average Molecular Weight ◽  
Weight Fraction ◽  
Considerable Proportion ◽  
Prolonged Storage ◽  
High Molecular Weight Fraction ◽  
The United Kingdom ◽  
Molecular Weight Fractions ◽  
Temperate Climates

Abstract Fractionation of the rubber hydrocarbon in temperate climates has usually resulted in high molecular-weight fractions, with a molecular weight of the order of one million. Bloomfield has shown that fresh latex contains a considerable proportion of hydrocarbon having an intrinsic viscosity (η) of 10 or over and, therefore, a molecular weight of well over 106. The fractionation technique used by Bloomfield in Malaya has now been applied by the writer to smoked sheet and to F rubber, working in the United Kingdom. No very high molecular-weight fractions were found in the smoked sheet, but the F rubber yielded a fraction of (η)=7.3 and a number average molecular weight 6×106, determined osmometrically. The average molecular weight of natural rubber when freshly prepared is probably well over a million, and includes a substantial portion having a molecular weight of several millions. By the time smoked sheet has reached temperate climates, the high molecular-weight portion has probably been converted to gel. F rubber, presumably because of its different method of preparation, retains the major part of its high molecular-weight material during prolonged storage.

Uptake of Zinc by the Aquatic Larvae of Simulium ornatipes (Diptera : Nematocera)

1978 ◽  
Vol 29 (3) ◽  
pp. 299 ◽  
Author(s):  
JGT Carter ◽  
WL Nicholas
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Free Water ◽  
Weight Fraction ◽  
The Body ◽  
Ion Concentration ◽  
High Molecular Weight Fraction ◽  
Phosphonic Acids ◽  
Calcium Ion Concentration ◽  
Molecular Weight Fractions

The uptake and loss of zinc by the aquatic larvae of the blackfly S. ornatipes was investigated using radioactive 65Zn. Larvae may absorb significant quantities of zinc from solution, and a substantial proportion remains in the body when larvae are transferred to zinc-free water. Uptake is assisted by metabolism, but an increase of the calcium ion concentration, although reducing toxicity, has no effect on uptake, exchange or the loss of zinc. Larvae may be fractionated into 'cuticle', 'high-' and 'low-molecular-weight' fractions, based on solubility in water and 80% (v/v) ethanol. In the cuticle and high-molecular-weight fractions two 'pools' may be identified by dialysis against Na3EDTA -a pool in which zinc is weakly held and exchanges rapidly with the zinc in solution, and one where zinc is held and exchanges slowly. Exposure time, temperature, and external concentration influence the quantity of zinc entering these pools. Washing the cuticle and high-molecular-weight fractions with a series of buffers suggests that zinc is bound by phenolic groups in the cuticle fraction, and by phosphonic acids in the high-molecular-weight fraction. Sulfhydryl groups did not bind a major portion of the zinc.

FRACTIONATION OF LIVER SOMATOMEDIN ACTIVITY BY ULTRAFILTRATION

1974 ◽  
Vol 62 (2) ◽  
pp. 355-361 ◽  
Author(s):  
JENNIFER M. DEHNEL ◽  
P. D. McCONAGHEY ◽  
M. J. O. FRANCIS
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
High Molecular Weight Fraction ◽  
Cartilage Growth ◽  
The Relationship ◽  
Somatomedin Inhibitors

SUMMARY Plasma somatomedin is the intermediary through which growth hormone (GH) exerts its effects on the growing skeleton. Somatomedin activity may be produced in vitro by perfusion of the liver and kidneys of rats with Waymouth's medium containing GH. The relationship between the activity of plasma somatomedin and somatomedin of hepatic and renal origin has yet to be clarified. Somatomedin from plasma can be separated into active fractions of both high and low molecular weight. Similarly, ultrafiltration of medium containing somatomedin of hepatic origin indicates the existence of two active fractions, one of high molecular weight (greater than 50000) and one of low molecular weight (less than 1000). The latter can be attributed to the release of amino acids, such as serine and glutamine, by the perfused tissue. The high molecular weight fraction is believed to represent GH-dependent somatomedin. Fractions that inhibit production of cartilage matrix are present in liver perfusates as well as in plasma. These results provide further evidence that the liver is a source of GH-dependent somatomedin in vivo. Furthermore, cartilage growth may be controlled not only by the GH-stimulated release of somatomedin by the liver, but also by its release of acid-labile somatomedin inhibitors.

Antithrombotic Properties Of Low Molecular Weight Heparin Fractions From Porcine Mucosal Heparin

1981 ◽  
Author(s):  
J Choay ◽  
Jean C Lormeau ◽  
Harry L Messmore ◽  
Jawed Fareed ◽  
J Stulc ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Prothrombin Complex Concentrate ◽  
Specific Activity ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Prothrombin Complex Concentrates ◽  
Heparin Fractions ◽  
Russell’S Viper ◽  
Molecular Weight Fractions

A previous report from our laboratories has described the extraction and physicochemical properties of a low molecular weight fraction (mol wt 4-8 × 103 daltons) from porcine mucosal heparin (Choay et. al. thrombosis Res 18, 573, 1980). Beside exhibiting a strong anti Xa (>250 u/mg) activity, this product possessed strong antithrombotic properties in a modified rabbit stasis thrombosis model. At a 125 anti Xa u/kg it protected the thrombotic effects of activated prothrombin complex concentrate (20 u/kg) and Prothrombin Complex Concentrate/Russell’s Viper Venom challenge in both the pretreatment and post-treatment regiments. At 1250 anti Xa u/kg SC it also showed antithrombotic effects for various periods. We have also obtained another low molecular weight fraction from porcine mucosal heparin by controlled depolymerization with nitrous acid. This product possessed saccharides with molecular weight ranging 3-6 × 103 daltons and exhibited a specific activity of >200 anti Xa u/mg. At a 125 anti Xa u/kg this product also showed antithrombotic activity against the thrombotic effects of activated prothrombin complex concentrates, prothrombin complex concentrates and Russell’s Viper Venom. In contrast to these two low molecular weight fractions porcine mucosal heparin in identical anti Xa units failed to produce protection against the thrombogenic stimuli. Our studies suggest that low molecular weight heparin fractions with strong anti Xa and antithrombotic activities can be obtained by chemical depolymerization. Furthermore, their biologic properties are found to be similar to the naturally occuring low molecular weight fractions present in native porcine mucosal heparin.

Breakdown of mucin and plant polysaccharides in the human colon

1977 ◽  
Vol 55 (11) ◽  
pp. 1190-1196 ◽  
Author(s):  
J. R. Vercellotti ◽  
A. A. Salyers ◽  
W. S. Bullard ◽  
T. D. Wilkins
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Subjects ◽  
Human Colon ◽  
Low Molecular Weight ◽  
High Molecular Weight Protein ◽  
Complex Carbohydrate ◽  
Plant Polysaccharides ◽  
Weight Protein ◽  
Molecular Weight Fractions

To obtain an estimate of the extent to which complex carbohydrates are degraded by bacteria in the human colon, aqueous extracts of colon contents from four human subjects were separated into high and low molecular weight fractions by chromatography on a Sephadex G-100 column. The composition of these fractions was compared with the composition of similar fractions from ileal contents, i.e., from material entering the colon. In all four subjects, high molecular weight carbohydrate concentrations were lower in the colon than in the ileum, indicating that breakdown of complex carbohydrate occurs in the colon. The high molecular weight carbohydrate fraction contained sugars characteristic of plant polysaccharides (arabinose, xylose, mannose, rhamnose) as well as sugars characteristic of mucin (fucose, hexosamines, sialic acids). Concentrations of most of these sugars were uniformly lower in the colon than in the ileum. Since high molecular weight protein concentrations were lower in the colon than in the ileum of two of the four subjects tested, some degradation of protein may also occur in the colon.

scholarly journals The Heterogeneity of the High Molecular Weight B12 Binder in Serum

Blood ◽  
1969 ◽  
Vol 33 (6) ◽  
pp. 899-908 ◽  
Author(s):  
CHRISTINE LAWRENCE
Keyword(s):  
Molecular Weight ◽  
Vitamin B12 ◽  
High Molecular Weight ◽  
Serum Proteins ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Transcobalamin I ◽  
Transcobalamin Ii

Abstract The binding of vitamin B12 by serum proteins was studied by separating Co57B12-enriched serum by Sephadex gel filtration, column chromatography with DEAE-cellulose, and paper electrophoresis. Each method of separation yielded two discrete B12-binding fractions. However, the analysis of each serum by all three separation technics indicated that one of the fractions was, in each case, bipartite. The "high" molecular weight B12-binding fraction defined by Sephadex gel filtration consisted of transcobalamin I and just part of the transcobalamin II fraction. The remaining portion of transcobalamin II was eluted from Sephadex gel in a "low" molecular weight fraction. Thus, transcobalamin II, equivalent to the β-globulin B12-binder, consisted of both "high" and "low" molecular weight components. This suggests that there are at least three serum proteins that can bind vitamin B12: two β-globulins, together comprising the transcobalamin II fraction and differing in molecular weight; and transcobalamin I.

scholarly journals Molecular-mass distribution of humus acids of taiga soils

2021 ◽  
Vol 4 (4) ◽  
Author(s):  
E. D. Lodygin ◽  
R. S. Vasilevich
Keyword(s):  
Molecular Weight ◽  
Molecular Mass ◽  
Molecular Mass Distribution ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Distilled Water ◽  
High Molecular Weight Fraction ◽  
Molecular Weights ◽  
Podzolic Horizon ◽  
Agricultural Use

Purpose of the study: to reveal the influence of hydromorphism and agricultural use on the molecular-mass distribution (MMD) of humic (HAs) and fulvic acids (FAs) isolated from the soils of the European northeast of Russia. To assess the influence of the acidity of the medium on the MWD of FAs. Place and time of the event. The studies were carried out on the territory of the middle taiga (Maksimovsky station of the Institute of Biology of the Federal Research Center of the KSC UB RAS, located 8 km west of the city of Syktyvkar and the field of the Syktyvkar state farm, 5 km south-west of Syktyvkar, on the watershed of the Sysola and Vazhel-yu rivers) and northern taiga (3 km west of the Troitsko-Pechorsk station). The objects of the study were humic substances isolated from typical podzolic (Eutric Albic Retisol (Loamic)), gleypodzolic (Eutric Albic Stagnic Retisol (Loamic)), peaty-podzolic surface-gleyed (Eutric Albic Stagnic Histic) Retisol (Loamic Eutric Albic Retisol (Loamic)) soils. The soil sampling period is from 1 to 30 August 2014. Methodology. Quantitative analysis of the MMD of HA and FA preparations was performed using liquid size exclusion chromatography (gel chromatography) on Sephadex G-25 and G-100 gels with continuous automatic registration of the optical density of the eluate (λ = 280 nm) in a quartz flow cell, K 9 × 60 cm column (Pharmacia, Sweden). Distilled water, 0.05 M NaOH solution, and Tris-HCl buffer with pH = 8.2 were used as the eluent. Main results. Studies of the MMD of humic substances have been carried out. It was found that HAs contain three fractions with different molecular weights: ≥ 150 kDa, 73–80 kDa, and 13–23 kDa; FAs – two fractions: ≥ 5 kDa, 1–2 kDa. The low molecular weight of FAs, together with a large amount of oxygen-containing functional groups, contributes to their better solubility and migration ability in soils. The HAs of automorphic soils are characterized by a high content of low molecular weight fractions, and the proportion of the high molecular weight fraction in the HAs of the litter is 1.5–2.0 times higher than in the HAs of the podzolic horizon, which may be due to the migration of the low molecular weight fraction down the profile. The high proportion of the acidic low molecular weight fraction in the podzolic horizon promotes the decomposition of soil minerals and their leaching into the illuvial horizon. The influence of agricultural use of soils on the fractional composition of humic compounds is estimated. A sharp increase in the share of the high molecular weight fraction in the preparations of HAs of arable podzolic soil by 2–4 times compared with the HAs of virgin podzolic soils was noted, which is due to the cultivation of the arable horizon, the nature of the incoming plant residues and the increased microbiological activity of the developed soils. The effect of acidity of the medium on the character of chromatograms of FA preparations isolated from the main types of soils of the Komi Republic was studied. It has been shown that in the region of high pH values of the eluent 9–13, the absence of fractionation is associated with the association of FAs, a change in their conformation, and the effect of “over-exclusion”. Elution with distilled water (pH = 6.5) allows the separation of FAs into two fractions with molecular weights ≥ 5 kDa and 1–2 kDa.

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