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)

Distribution of high-molecular-weight n-alkanes in paraffinic crude oils and asphaltene-resin-paraffin deposits

2010 ◽  
Vol 50 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Yu. M. Ganeeva ◽  
T. R. Foss ◽  
T. N. Yusupova ◽  
A. G. Romanov
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Crude Oils ◽  
Paraffinic Crude

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).

High molecular weight aromatic nitrogen and other novel hopanoid-related compounds in crude oils

2004 ◽  
Vol 35 (6) ◽  
pp. 665-678 ◽  
Author(s):  
T.B.P Oldenburg ◽  
H Huang ◽  
P Donohoe ◽  
H Willsch ◽  
S.R Larter
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Crude Oils ◽  
Related Compounds

scholarly journals Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

2009 ◽  
Vol 9 (7) ◽  
pp. 2289-2300 ◽  
Author(s):  
E. L. Shapiro ◽  
J. Szprengiel ◽  
N. Sareen ◽  
C. N. Jen ◽  
M. R. Giordano ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Inorganic Salt ◽  
Aerosol Particles ◽  
Ammonium Ion ◽  
Pendant Drop ◽  
Tropospheric Aerosol ◽  
Surface Active ◽  
Visible Wavelengths ◽  
Seed Aerosol

Abstract. Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4) aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu) products were observed when ammonium sulfate ((NH4)2SO4) or sodium chloride (NaCl) was present in the aqueous phase. The products formed in (NH4)2SO4 or ammonium nitrate (NH4NO3) solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest a mechanism involving the participation of the ammonium ion. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

scholarly journals Bacterial surfactants as agents with antibiofilm activity

2021 ◽  
Vol 16 (1) ◽  
pp. 94-104
Author(s):  
А.Е. Abaturov
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Antibiofilm Activity ◽  
Antibiotic Resistant ◽  
Biological Surface ◽  
The Matrix ◽  
Surface Active ◽  
Bacteria And Fungi ◽  
Surface Active Compounds

Biosuragents are a heterogeneous group of biological surface-active amphiphilic compounds. The producers of biosurfactants are various microorganisms: bacteria and fungi. The class of biosurfactants consists of two groups: low molecular weight and high molecular weight compounds. Representatives of low molecular weight compounds are lipopeptides, glycolipids, fatty acids, phospholipids that reduce surface and interfacial tension, and high molecular weight compounds are polymer and dispersed biosurfactants, which are emulsion stabilizers. The most studied biosurfactants with the potential of drugs are lipopeptides and glycolipids. A subgroup of lipopeptides are polymyxins, pseudo-factins, putisolvins, surfactin, fengycin and others; and glycoli­pids — rhamnolipids, trehalose, sophorose, cellobiose, mannosileritritol lipids, and others. Biosurfactants play a key role in the life of biofilms: they regulate the adhesion of bacteria and biofilm matrix, support the functioning of the matrix channels, providing the nutrient needs of bacteria. It has also been shown that biosurfactants are involved in the formation and dispersion of formed biofilms. These substances, directly reacting with the components of the matrix, induce degradation of the biofilm. Biosurfing agents, possessing antimicrobial, antifungal and antiviral, and antitumor properties, are a promising class of compounds that, possessing a combination of antibacterial and antibiofilm action, open up new perspectives in the treatment of recurrent chronic infectious di­seases. It is believed that surface-active compounds, both representatives of lipopeptides and glycolipids, can be the molecular basis for the development of drugs that will enhance the effectiveness of antibiotic therapy for problem infections, especially those caused by antibiotic-resistant strains.

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