Induced Phase Separation in Low-Ionic-Strength Cellulose Nanocrystal Suspensions Containing High-Molecular-Weight Blue Dextrans

Langmuir ◽  
2006 ◽  
Vol 22 (21) ◽  
pp. 8690-8695 ◽  
Author(s):  
Stephanie Beck-Candanedo ◽  
David Viet ◽  
Derek G. Gray
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Ionic Strength ◽  
High Molecular Weight ◽  
Cellulose Nanocrystal ◽  
Low Ionic Strength

scholarly journals Production and characterisation of a marine Halomonas surface-active exopolymer

2019 ◽  
Vol 104 (3) ◽  
pp. 1063-1076
Author(s):  
Tony Gutierrez ◽  
Gordon Morris ◽  
Dave Ellis ◽  
Barbara Mulloy ◽  
Michael D. Aitken
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
High Molecular Weight ◽  
Positive Influence ◽  
Contaminated Sites ◽  
Crude Oils ◽  
Magnetic Resonance Spectroscopic Analysis ◽  
Surface Active ◽  
Low Ionic Strength ◽  
Pure Hydrocarbon

AbstractDuring screening for novel emulsifiers and surfactants, a marine gammaproteobacterium, Halomonas sp. MCTG39a, was isolated and selected for its production of an extracellular emulsifying agent, P39a. This polymer was produced by the new isolate during growth in a modified Zobell’s 2216 medium amended with 1% glucose, and was extractable by cold ethanol precipitation. Chemical, chromatographic and nuclear magnetic resonance spectroscopic analysis confirmed P39a to be a high-molecular-weight (~ 261,000 g/mol) glycoprotein composed of carbohydrate (17.2%) and protein (36.4%). The polymer exhibited high emulsifying activities against a range of oil substrates that included straight-chain aliphatics, mono- and alkyl- aromatics and cycloparaffins. In general, higher emulsification values were measured under low (0.1 M PBS) compared to high (synthetic seawater) ionic strength conditions, indicating that low ionic strength is more favourable for emulsification by the P39a polymer. However, as observed with other bacterial emulsifying agents, the polymer emulsified some aromatic hydrocarbon species, as well as refined and crude oils, more effectively under high ionic strength conditions, which we posit could be due to steric adsorption to these substrates as may be conferred by the protein fraction of the polymer. Furthermore, the polymer effected a positive influence on the degradation of phenanthrene by other marine bacteria, such as the specialist PAH-degrader Polycyclovorans algicola. Collectively, based on the ability of this Halomonas high-molecular-weight glycoprotein to emulsify a range of pure hydrocarbon species, as well as refined and crude oils, it shows promise for the bioremediation of contaminated sites.

The oligomeric state of spectrin in the rat erythrocyte membrane skeleton

1990 ◽  
Vol 68 (6) ◽  
pp. 936-943 ◽  
Author(s):  
Ross A. Avery ◽  
William J. Bettger
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
High Molecular Weight ◽  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Protein A ◽  
Membrane Skeleton ◽  
Oligomeric State ◽  
High Molecular Weight Complex ◽  
Low Ionic Strength

The oligomeric state of spectrin in the erythrocyte membrane skeleton of the rat was investigated following extraction in a low ionic strength buffer for 24 and 96 h. All analyses were quantitively compared with preparations from human erythrocyte membranes. After nondenaturing agarose–polyacrylamide gel electrophoresis, the human samples revealed their characteristic spectrin oligomer pattern; there were high molecular weight complexes near the origin of the gel, followed by several high order oligomers, tetramers, and dimers. The pattern in the rat membrane skeleton also included tetramers and a high molecular weight complex band, but had only one oligomer and no dimers. With time the high molecular weight complex diminished and oligomers accumulated in both the rat and human, while dimers accumulated only in the human and tetramers accumulated only in the rat. Tetramers decreased with time in the human. Extraction of spectrin increased with time and was greater from rat than the human red cell membrane at both time points. The percentage of spectrin and actin in the low ionic strength extract was similar between species, as analyzed by SDS–polyacrylamide electrophoresis, staining, and densitometry. Proteins 4.1 and 4.9 were present in greater percentages in the human. The only temporal effect on monomeric protein composition was an increase of protein A in the rat. There was no species difference in protein A percentage at 24 h, but at 96 h the rat was greater than the human. The results suggest that there are significant differences in the structural arrangement of the rat and human erythrocyte membrane skeleton.Key words: spectrin, erythrocyte, membrane, cytoskeleton.

scholarly journals Enhanced reactive lysis of paroxysmal nocturnal hemoglobinuria erythrocytes. Studies on C9 binding and incorporation into high molecular weight complexes.

1986 ◽  
Vol 164 (4) ◽  
pp. 981-997 ◽  
Author(s):  
S I Rosenfeld ◽  
D E Jenkins ◽  
J P Leddy
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
High Molecular Weight ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Specific Binding ◽  
Type Iii ◽  
Normal Human ◽  
Membrane Bound ◽  
Low Ionic Strength

As part of a broader analysis of the mechanism(s) by which the most sensitive (type III) paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes are excessively sensitive to reactive lysis by isolated C5b6, C7, C8, and C9, we have compared type III PNH (PNH-III) and normal human E in respect to both total specific binding of 125I-C9 and the proportion of cell-bound C9 appearing in high molecular weight (HMW) complexes. In a previous report, we found that after exposure to purified C5b6 and 125I-C7, specific C7 binding and, by implication, EC5b-7 formation were equal for PNH-III E and normal E. In the present study, C8-dependent binding of 125I-C9 to PNH-III EC5b-7 and normal EC5b-7 was also similar, although lysis of the PNH-III E was up to five times greater; that is, PNH-III E required fewer bound C9 molecules to produce an effective lytic site than did normal E. To quantify radioactivity in monomeric and HMW forms of membrane-bound C9, lysed and unlysed E were subjected to low ionic strength buffers to convert all E to ghosts. These ghosts were solubilized in 0.1 or 2% SDS (without reduction) and electrophoresed on 2.4-11% polyacrylamide gradient gels followed by autoradiography and densitometric scanning. With 0.1% SDS, broad, heterodisperse zones of HMW C9 were recovered from both PNH and normal ghosts; the amounts of C9 incorporated into the HMW complexes were similar for PNH-III E and normal E. In selected experiments, 125I-C7 could be shown in these same HMW bands. When membranes were solubilized in 2% SDS, the overall proportion of HMW C9 complexes compared with dimer and monomer C9 was reduced on both PNH and normal membranes. In many, but not all experiments, more of the highest mol wt C9 complexes were detected from PNH-III E membranes solubilized in 2% SDS than from normal or PNH-II E membranes similarly treated. When antibody-sensitized E were lysed by purified C1-C9, PNH-III EA bound far more C9 than did normal EA, and both lysis and C9 incorporation into HMW complexes were markedly and proportionately increased over normal; however, lytic efficiency of 125I-C9 bound to PNH EA was equal to or less than that bound to normal EA.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereo-chemical contributions to the glass transition and liquid–liquid phase separation in high molecular weight poly(N-vinyl carbazole)

RSC Advances ◽  
2016 ◽  
Vol 6 (35) ◽  
pp. 29326-29333 ◽  
Author(s):  
Abdul G. Al Lafi ◽  
James N. Hay
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Phase Separation ◽  
Liquid Phase ◽  
High Molecular Weight ◽  
Structural Properties ◽  
Thermal History ◽  
Liquid Phase Separation ◽  
High Molecular Weight Poly ◽  
Liquid Liquid Phase Separation

Thermal history and purification effects on the structural properties of PVK were investigated. Liquid–liquid phase separation is suggested to occur by separation of isotactic rich segments from a matrix which is predominantly atactic.

scholarly journals Protein diffusion through charged nanopores with different radii at low ionic strength

2014 ◽  
Vol 16 (39) ◽  
pp. 21570-21576 ◽  
Author(s):  
Pieter Stroeve ◽  
Masoud Rahman ◽  
Lekkala Dev Naidu ◽  
Gilbert Chu ◽  
Morteza Mahmoudi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Protein Diffusion ◽  
Similar Molecular Weight ◽  
Low Ionic Strength ◽  
Charged Membranes ◽  
Pore Permeability

Pore permeability for two similar molecular weight proteins (BSA and BHb) through nanoporous charged membranes at low ionic strength (I = 0.001 M).

Human and Bovine Plasminogen-Free Thrombin, Purified by Means of Gel Filtration and Ion Exchange Chromatography

1966 ◽  
Vol 15 (03/04) ◽  
pp. 501-510 ◽  
Author(s):  
W Berg ◽  
K Korsan-Bengtsen ◽  
J Ygge
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Large Scale ◽  
Gel Filtration ◽  
Trisodium Citrate ◽  
Exchange Chromatography ◽  
Simple Method ◽  
Commercial Preparation ◽  
Usual Manner ◽  
Low Ionic Strength

SummaryA simple method for preparation of plasminogen-free human and bovine thrombin is described.Crude thrombin was prepared in the usual manner from oxalated plasma by means of adsorption on BaSO4, elution with trisodium citrate and activating the eluate from BaSO4 with tissue thromboplastin.This crude thrombin was purified by means of gel-filtration and chromatography on CM-Sephadex A-50.The gel-filtration was performed on three types of Sephadex, G-75, G-50, and G--25. By means of Sephadex G-75 the thrombin was well separated from the main part of inert protein and this type of Sephadex was used for the purification in large-scale. Separation of thrombin from protein of higher molecular weight was also obtained with Sephadex G-50 but not with Sephadex G-25 indicating a molecular weight of thrombin between 4000 and 10,000.The importance of using an elution buffer of sufficient high ionic strength for gel-filtration is shown. A great deal of the thrombin was adsorbed to the Sephadex if the gel-filtration was performed at a too low ionic strength.The final preparation contained 30,000 NIH units of thrombin per mg tyrosin and no detectable plasminogen.The commercial preparation “Topostasine” was also purified in the same manner, but the plasminogen content in “Topostasine” was high and could not be completely separated from thrombin.

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