Interaction of monomeric and polymeric species of metal ions with clay surfaces. III. Aluminium(III) and chromium(III)

Soil Research ◽  
1978 ◽  
Vol 16 (1) ◽  
pp. 53 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Molecular Weight ◽  
Metal Ion ◽  
Negative Charge ◽  
Positive Charge ◽  
Gel Filtration ◽  
Charge Reversal ◽  
Original Solution ◽  
Polymeric Species ◽  
Surface Hydroxyls ◽  
Nitrate Solutions

Hydrolysis and polymerization in aluminium nitrate and chromic nitrate solutions with different metal/OH ratios were studied by gel filtration chromatography and ultrafiltration techniques. The characteristics of poly[Al(III)-OH] cations separated by ultrafiltration depended on the molecular weight which was controlled by the OH/Al ratio of the original solution. When the OH/Al ratio was <2.0, the polycations had molecular weight < 50 000, high positive charge and were stable. When the ratio was > 2.0 , the polycations had molecular weight > 100 000, low positive charge and rapidly condensed to gibbsite. Polymerization in chromic nitrate solutions was slow and the separated poly[Cr(III)-OH] cations had low molecular weight (<20000), high positive charge and were stable. The interaction of monomeric and polymeric species of aluminium(III) and chromium(III) with the surfaces of sodium-kaolinite, sodium-bentonite and sodium-illite was studied using hydrolysed nitrate solutions of aluminium and chromium, and separated polycations. The results obtained were consistent with the earlier observations of the iron(III) system, and the behaviour could be explained on the basis of positive charge and probable structure of polycations. The adsorption of aluminium(III) and chromium(III) on clay surfaces from hydrolysed metal ion solutions was related to OH/Al or OH/Cr ratios and pH. The adsorption of polycations was low and related to their positive charge. Maximum adsorption resulted in charge reversal on clays. Addition of the hydrolysed nitrate solutions to clays also caused charge reversal and reduction of negative charge. The adsorption from a mixture of monomers and polymers on bentonite surfaces reduced negative charge markedly due to interlayer formation, while the adsorption of separated polycations in low amounts neutralized the charge on surface hydroxyls and led to the flocculation of clays. The anomalous behaviour of the poly[Al(III)-OH] cations of molecular weight >100 000 could be explained if they consisted of planar sheets, formed from coalesced rings of aluminium octahedra, which crystallized into gibbsite.

Interaction of monomeric and polymeric species of metal ions with clay surfaces. II. Changes in surface properties of clays after addition of iron(III)

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 235 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Negative Charge ◽  
Point Of Zero Charge ◽  
Ferric Nitrate ◽  
Net Charge ◽  
Clay Particles ◽  
Polymer Bridging ◽  
Ph Values ◽  
Polymeric Species ◽  
Surface Hydroxyls ◽  
Nitrate Solutions

The adsorption of poly [Fe(III)-OH] cation by claysurfaces led to flocculation of clay particles possibly by polymer bridging while the addition of iron(III) from hydrolysed ferric nitrate solutions resulted in flocculation and cementation by precipitated iron(III). Electrokinetically clays with adsorbed iron(III) behaved similarly to amorphous ferric hydroxides with positive mobilities below the point of zero charge (PZC). Polycations reversed the charge on the clay particles at maximum adsorption, which probably represents neutralization of charge due to surface hydroxyls. When hydrolysed ferric nitrate solutions were added to kaolinite and illite charge reversal occurred at pH values below 6. Adsorption of iron(III) resulted in a partial reduction of negative charge in clays. The reduction of negative charge in kaolinite and illite was close to the charge due to surface hydroxyls. The net charge estimated at all pH values corresponded with the electrophoretic mobility in all the iron(III) clay complexes except bentonite with adsorbed polycations.

Interaction of monomeric and polymeric species of metal ions with clay surfaces. I. Adsorption of iron(III) species

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 221 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Iron Atom ◽  
Positive Charge ◽  
Molecular Size ◽  
Ferric Nitrate ◽  
Distilled Water ◽  
Critical Coagulation Concentration ◽  
Sodium Bentonite ◽  
Polymeric Species ◽  
Surface Hydroxyls ◽  
Nitrate Solutions

Uitrafiltration or dialysis against distilled water was used to separate polymerized ferric hydroxy cations from the monomeric cations in hydrolysed solutions of ferric nitrate. Separated poly[Fe(III)-OH] cations were polydispersed and the positive charge was inversely related to molecular size. The separated poly[Fe(III)-OH] cations were found to be stable and did not condense further during a period of 6 months. The association of iron(III) with the surfaces of sodium-kaolinite, sodium-bentonite and sodiumillite was studied using hydrolysed ferric nitrate solutions and separated poly[Fe(III)-OH] cations. As the OH/Fe ratio (and pH) of the ferric nitrate solutions increased, the critical coagulation concentration (CCC) and the maximum adsorption of iron(III) increased. The amount of iron adsorbed in the form of separated po1y[Fe(III)-OH] cations was small and was related to the positive charge per iron atom of the polycations. It is proposed that iron(III) in solutions containing only polycations and solutions containing a mixture of mono- and polycations reacted differently with clay surfaces. A reaction of polycations with the surface hydroxyls leading to chemisorption and irreversible flocculation of clays is proposed.

scholarly journals Purification and Electrophoretic Behavior of Sugarcane Invertases

1969 ◽  
Vol 51 (1) ◽  
pp. 39-45
Author(s):  
Alex G. Alexander
Keyword(s):  
Enzyme Purification ◽  
Negative Charge ◽  
Positive Charge ◽  
Gel Filtration ◽  
Paper Electrophoresis ◽  
Good Separation ◽  
Electrophoretic Behavior ◽  
Negative Electrodes ◽  
Differential Solubility ◽  
Fair Degree

A fair degree of sugarcane invertase purification has been achieved by techniques of differential solubility, gel filtration, and paper electrophoresis. Invertase is readily salted out with ammoniun sulfate between 38- and 52- percent saturation. Activity is largely lost during dialysis against distilled water, but is regained by passage through columns of G-200 Sephadex gel. Reactivation is attributed to removal of unknown inhibitors. Filtration did not accomplish good separation of invertase from other protein. Electrophoresis experiments showed that invertases are quite mobile compared to contaminant protein, and move quickly toward positive and negative electrodes. Two distinct invertase areas were obtained free of contaminant protein, one enzyme bearing a positive charge and the other a negative charge. Filtration and electrophoresis steps described herein achieved good enzyme purification without use of glucose or manganese, and thus avoided the appearance of reconstituted invertase.

scholarly journals The ionic interaction of Klebsiella pneumoniae K2 capsule and core lipopolysaccharide

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1807-1818 ◽  
Author(s):  
Sandra Fresno ◽  
Natalia Jiménez ◽  
Luis Izquierdo ◽  
Susana Merino ◽  
Maria Michela Corsaro ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Metal Ion ◽  
Galacturonic Acid ◽  
Capsular Polysaccharide ◽  
Negative Charge ◽  
Gel Filtration ◽  
Carboxyl Groups ◽  
Ionic Interaction ◽  
Phenol Water ◽  
Metal Ion Chelators

The complete structures of LPS core types 1 and 2 from Klebsiella pneumoniae have been described by other authors. They are characterized by a lack of phosphoryl residues, but they contain galacturonic acid (GalA) residues, which contribute to the necessary negative charges. The presence of a capsule was determined in core-LPS non-polar mutants from strains 52145 (O1 : K2), DL1 (O1 : K1) and C3 (O8 : K66). O-antigen ligase (waaL) mutants produced a capsule. Core mutants containing the GalA residues were capsulated, while those lacking the residues were non capsulated. Since the proteins involved in the transfer of GalA (WabG) and glucosamine residues (WabH) are known, the chemical basis of the capsular-K2–cell-surface association was studied. Phenol/water extracts from K. pneumoniae 52145ΔwabH waaL and 52145ΔwaaL mutants, but not those from from K. pneumoniae 52145ΔwabG waaL mutant, contained both LPS and capsular polysaccharide, even after hydrophobic chromatography. The two polysaccharides were dissociated by gel-filtration chromatography, eluting with detergent and metal-ion chelators. From these results, it is concluded that the K2 capsular polysaccharide is associated by an ionic interaction to the LPS through the negative charge provided by the carboxyl groups of the GalA residues.

scholarly journals Purification and properties of a manganese-stimulated deoxyribonuclease produced during sporulation of Bacillus subtilis

1978 ◽  
Vol 172 (1) ◽  
pp. 69-76 ◽  
Author(s):  
A Akrigg
Keyword(s):  
Molecular Weight ◽  
Bacillus Subtilis ◽  
Metal Ion ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Duplex Dna ◽  
Ph Optimum ◽  
Endonucleolytic Cleavage ◽  
Single Strand Breaks ◽  
Purification And Properties

A DNAase (deoxyribonuclease) was isolated from culture supernatants of sporulating Bacillus subtilis 168. The purified enzyme migrated as a single band during polyacrylamide-gel electrophoresis. The enzyme differs from other DNAases of B. subtilis in molecular weight, metal-ion requirement and mode of action. The enzyme was inactive in the absence of metal ions, and exhibited optimum activity with 10 mM-Mn2+, although Mg2+, Cd2+ and Co2+ could also permit some activity. The pH optimum for the enzyme was pH 7.5, and it degraded linear-duplex DNA or closed-circular-duplex DNA to acid-soluble material. There was little or no activity on single-stranded DNA or rRNA. Sucrose-gradient analysis of the products of DNAase action on bacteriophage T7 DNA showed that endonucleolytic cleavage had occurred by the introduction of single-strand breaks in both strands of the duplex. The molecular weight of the enzyme was determined, by gel filtration on Sephadex G-75, to be 12000.

α-Glutamic acid-β-naphthylamidase from Neisseria catarrhalis

1969 ◽  
Vol 15 (11) ◽  
pp. 1293-1300 ◽  
Author(s):  
Sidney T. Cox ◽  
Francis J. Behal
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Metal Ion ◽  
Gel Filtration ◽  
Aminopeptidase Activity ◽  
Amino Acid Residues ◽  
Ph Optimum ◽  
Hydrolysis Of ◽  
Derivatives Of

A second bacterial peptidase-like enzyme, arylamidase-II, has been isolated from cell free extracts of Neisseria catarrhalis. Arylamidase-II action is limited primarily to the hydrolysis of α-glutamic acid and α-aspartic acid derivatives of β-naphthylamine and short peptides of glutamic acid. The enzyme was purified 450-fold by gel filtration, ion exchange, and calcium phosphate chromatography. Its pH optimum and molecular weight were 7.7 and 170 000, respectively. Aside from its restricted substrate specificity, arylamidase-II has been found to be closely related in its mechanism of action, molecular weight, pH optimum, and metal ion dependence to arylamidase-I, which catalyzes the hydrolysis of neutral amino acid derivatives of β-naphthylamine. Arylamidase-II exhibits aminopeptidase activity, requiring the amino acid residues in the N-terminal and penultimate position to be of the L-configuration in order for hydrolysis to occur.

scholarly journals Purification, Characterization and Antioxidant Potential of a Novel Lectin from Pterocarpus soyauxii Taub Seeds

2019 ◽  
Vol 11 (1) ◽  
pp. 112-121
Author(s):  
Oludele Olayemi ODEKANYIN ◽  
Atinuke Shakirat KAYODE ◽  
Joseph Olufemi ADEWUYI
Keyword(s):  
Lipid Peroxidation ◽  
Molecular Weight ◽  
Metal Ion ◽  
Radical Scavenging ◽  
Gel Filtration ◽  
Antioxidant Potential ◽  
Dpph Radical ◽  
Subunit Molecular Weight ◽  
Ammonium Sulphate Precipitation ◽  
Lipid Peroxidation Inhibition

The study investigated the presence of lectin in the seeds of Pterocarpus soyauxii, purified the lectin and determined its physicochemical properties as well as its antioxidant potential. Purification of P. soyauxii seeds lectin (PSSL) was accomplished by ammonium sulphate precipitation and gel filtration on Sephadex G-100, hemagglutination assay was by serial dilution and DPPH radical scavenging, metal chelating and lipid peroxidation inhibition assays were employed to evaluate its antioxidant potential. PSSL agglutinated erythrocytes from human blood group ABO, rabbit and rat. Trypsinization enhanced agglutination which was inhibited by galactose, lactose and arabinose. The lectin activity was independent of metal ion, thermal stable up to 60 °C and at pH range of 6 to 8. Gel filtration estimated molecular weight was 65 kDa and subunit molecular weight was 35 kDa. PSSL showed significant antioxidant activity. The lectin was able to scavenge DPPH radical, chelate iron metal and inhibit lipid peroxidation with IC50 of 0.14 ± 1.33 mg/ml, 3.40 ± 0.37 mg/ml and 0.50 ± 0.08 mg/ml respectively. The results indicate that PSSL might be applied as natural antioxidant for the development of drug and food products for the benefit of human health.

scholarly journals Probing the active site of cytoplasmic aldehyde dehydrogenase with a chromophoric reporter group

1994 ◽  
Vol 300 (1) ◽  
pp. 25-30 ◽  
Author(s):  
T M Kitson ◽  
K E Kitson
Keyword(s):  
Aldehyde Dehydrogenase ◽  
Active Site ◽  
Negative Charge ◽  
Positive Charge ◽  
Gel Filtration ◽  
Modified Enzyme ◽  
Covalently Linked ◽  
Reporter Group

3,4-Dihydro-3-methyl-6-nitro-2H-1,3-benzoxazin-2-one (‘DMNB’) reacts with cytoplasmic aldehyde dehydrogenase in a similar way to that previously observed with the structurally related p-nitrophenyl dimethylcarbamate, but provides a covalently linked p-nitrophenol-containing reporter group at the enzyme's active site. The pKa of the enzyme-linked reporter group is much higher than that of free p-nitrophenol, which is consistent with its being in a very hydrophobic environment, or possibly one containing negative charge. Upon binding of NAD+ to the modified enzyme, the pKa falls dramatically, by about 4 1/2 pH units. This implies that under these conditions there is a positive charge near the p-nitrophenoxide moiety, perhaps that of the nicotinamide ring of NAD+. The modified enzyme binds NAD+ very tightly; neither gel filtration nor dialysis is effective in separating them. However, the reporter group provides a convenient way of monitoring the displacement of this bound NAD+ when NADH is added.

Changes in the surface charge of bacteria caused by heavy metals do not affect survival

1996 ◽  
Vol 42 (7) ◽  
pp. 621-627 ◽  
Author(s):  
Y. E. Collins ◽  
G. Stotzky
Keyword(s):  
Heavy Metals ◽  
Surface Charge ◽  
Negative Charge ◽  
Positive Charge ◽  
Agrobacterium Radiobacter ◽  
Charge Reversal ◽  
Ph Values ◽  
A Charge ◽  
Net Positive Charge ◽  
Cu And Zn

Bacillus subtilis and Agrobacterium radiobacter remained viable when exposed to Ni (1 × 10−4 M; ionic strength (μ) = 3 × 10−4) at pH values known to cause a change of the net negative charge of the cells to a net positive charge (charge reversal). The gross morphology, as determined by scanning electron microscopy, of these and other bacteria and of Saccharomyces cerevisiae was not altered in the presence of Ni, Cu, and Zn (1 × 10−4 M; μ = 3 × 10−4), which caused a charge reversal at pH values between 6.0 and 9.0. Similar results were obtained in the presence of Na and Mg, which did not cause charge reversal at the same μ and pH values. These results confirmed that cells remain viable when their surface charge is changed in the presence of some heavy metals at high pH values.Key words: heavy metals, electrokinetic properties, survival of bacteria.

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