Binding of lead cations to oligogalacturonic acids

1982 ◽  
Vol 47 (12) ◽  
pp. 3424-3431 ◽  
Author(s):  
Rudolf Kohn
Keyword(s):  
Human Body ◽  
Calcium Ions ◽  
Galacturonic Acid ◽  
Uronic Acid ◽  
The Other ◽  
Carboxyl Groups ◽  
Polymeric Chain ◽  
Polymerization Degree ◽  
Strong Decrease ◽  
Nitrate Ions

The activity of Pb2+ ions in solutions of lead oligogalacturonates of polymerization degree DP 1 to 5 (starting concentration of the investigated solutions 3.00 mmol (COOPb0.5) l-1, the ionic strenght of the solution I = 0.01 mol l-1, electrolyte KNO3, was determined by lead specific ion electrodes. The activity aPb2+ is independent on the kind of anion in very diluted solutions of lead perchlorate and nitrate. Ions of lead become bound quite firmly even to the monomeric D-galacturonic acid (association degree of Pb2+ ions to carboxyl groups of uronic acid β = 0.43). The increase of polymerization degree is associated with a strong decrease of the lead oligogalacturonate solubilities on one hand, and increase of the bond strenght of the Pb2+ ions to these oligomers on the other. The association degree of Pb2+ ions to carboxyl groups of the pentamer (β = 0.96) almost reaches the value found for the polymeric chain of pectate molecule (D-galacturonan); here, the stoichiometric binding of Pb2+ to two carboxyl groups takes place with a great deal of probability. Lead has been found to bind highly preferentially to oligogalacturonates even in the presence of calcium ions. Results presented in this paper help to clear the mechanism of elimination of lead from the human body through pectin and its oligomeric fragments.

Intramolecular binding of calcium ions to L-guluronan and D-galacturonan

1981 ◽  
Vol 46 (7) ◽  
pp. 1701-1707 ◽  
Author(s):  
Rudolf Kohn ◽  
Anna Malovíková
Keyword(s):  
Activity Coefficients ◽  
Calcium Ions ◽  
Uronic Acid ◽  
Total Activity ◽  
Polymeric Chain ◽  
Polymerization Degree ◽  
Pectic Acid ◽  
Calcium Salts ◽  
Macromolecule Chain ◽  
Derivatives Of

The values of activity coefficients γCa2+, determined earlier in solutions of calcium oligoguluronates and oligogalacturonates of various polymerization degree n, were interpreted. Values γCa2+ corresponding to an intramolecular Ca2+ bond to a polymeric chain of L-guluronan and D-galacturonan were obtained by extrapolation of functions γCa2+ = f(1/n) and γCa2+ = f((n-2)/n) to lim n → ##h. The γCa2+ values were compared with those determined in solutions of calcium salts of O-acetyl derivatives of pectic acid and D-mannuronan. In molecular disperse solutions the Ca2+ ions are bound to L-guluronan and D-galacturonan by an electrostatic bond. The course of the above-mentioned functions leads to the conclusion that both terminal uronic acid units in polyuronates under study bind Ca2+ ions less firmly than do the inner units in the macromolecule chain. The linear course of the function γCa2+ = f((n-2)/n) for L-guluronan proves the additivity of contribution of the terminal and inner uronic acid units to the total activity of Ca2+ counterions bound to L-guluronan.

Binding of lead and copper(II) cations to hemicelluloses of rye bran

1986 ◽  
Vol 51 (10) ◽  
pp. 2250-2258 ◽  
Author(s):  
Rudolf Kohn ◽  
Zdena Hromádková ◽  
Anna Ebringerová
Keyword(s):  
Uronic Acid ◽  
Equilibrium Solution ◽  
Glucuronic Acid ◽  
The Other ◽  
Carboxyl Groups ◽  
Stoichiometric Ratio ◽  
Molar Ratios ◽  
Free Ions ◽  
Uronic Acid Content ◽  
The Relationship

Several fractions of acid hemicelluloses isolated from rye bran were characterized by molar ratios of saccharides (D-Xyl, L-Ara, D-Glc, D-Gal) and 4-O-methyl-D-glucuronic acid and protein content. Binding of Pb2+ and Cu2+ ions to these acid polysaccharides was considered according to function (M)b = f([M2+]f), expressing the relationship between the amount of metal (M)b bound to 1 g of the substance and the concentration of free ions [M2+]f in the equilibrium solution and according to the association degree β of these cations with carboxyl groups of uronic acid at a stoichiometric ratio of both components in the system under investigation. Acid hemicelluloses contained only a very small portion of uronic acid ((COOH) 0.05-0.18 mmol g-1); the model polysaccharide, 4-O-methyl-D-glucurono-D-xylan of beech, was substantially richer in uronic acid content ((COOH) 0.73 mmol g-1). Consequently, the amount of lead and copper bound to acid hemicelluloses is very small ((M)b 0.017-0.025 mmol g-1) at [M2+]f = 0.10 mmol l-1. On the other hand, much greater amount of cations ((M)f 0.09-0.10 mmol g-1) was bound to the glucuronoxylan. The association degree β was like with the majority of samples (β = 0.31-0.38). The amount of lead and copper(II) bound to acid hemicelluloses from rye bran is several times lower than that bound to dietary fiber isolated from vegetables (cabbage, carrot), rich in pectic substances.

Binding of zinc cations to pectin and its oligomeric fragments

1983 ◽  
Vol 48 (11) ◽  
pp. 3154-3165 ◽  
Author(s):  
Anna Malovíková ◽  
Rudolf Kohn
Keyword(s):  
Human Body ◽  
Carboxyl Groups ◽  
Zinc Ions ◽  
Logarithmic Function ◽  
Polymerization Degree ◽  
Continuous Increase ◽  
The Stability ◽  
Esterification Degree ◽  
Zinc Cations ◽  
Degree Of Association

The activity of Zn2+ ions bound to carboxyl groups of pectin of esterification degree E 0 to 90% and to oligomeric potassium galacturonates of polymerization degree 1 to 7 was estimated by the metallochromic indicator (tetramethylmurexide) method. The zinc ions are stoichiometrically bound to pectin, one Zn2+ cation to two free carboxyl groups. The stability constant K of zinc pectinates strongly decreases with the increasing esterification degree in a relationship close to a linear logarithmic function, log K = f(E) similarly, as with the binding of Ca2+ ions to pectin. Pectin reveals a little higher selectivity to Zn2+ ions when considering this couple of cations. The zinc ions are bound to the monomeric D-galacturonic acid to a very low extent in contrast to some toxic cations as e.g. Pb2+, Cu2+, and Cd2+. A continuous increase of the degree of association of Zn2+ ions with carboxyl groups of oligomers takes place with the increasing polymerization degree. The validity of the increment additivity of terminal and inner uronic acid units to the final activity of zinc counterions bound to these oligomers was proved. The results are discussed from the standpoint of application of pectin as an active component of prophylactic diets against poisoning with cations of toxic metals with respect to the excretion of Zn2+ ions from the human body. Findings concerning the interaction of Zn2+ ions with pectin in dependence on its esterification degree (E) constitute a theoretical basis for a potential application of pectin as a useful ligand of Zn2+ ions in medical treatment of zinc deficiency in the human body.

Binding of cadmium and copper(II) ions to oligogalacturonic acids

1983 ◽  
Vol 48 (7) ◽  
pp. 1922-1935 ◽  
Author(s):  
Rudolf Kohn ◽  
Kveta Heinrichová ◽  
Anna Malovíková
Keyword(s):  
Uronic Acid ◽  
Multiple Equilibria ◽  
Carboxyl Groups ◽  
Polymerization Degree ◽  
Indicator Method ◽  
Ion Activity ◽  
Elimination Mechanism ◽  
Single Ion Activity ◽  
Degree Of Association ◽  
Positively Charged

The binding of Cu2+ and Cd2+ ions to potassium oligogalacturonates of polymerization degree DP 1 to 9 was investigated by ion-specific electrodes and by the metallochromic indicator method. The interaction was evaluated on the basis of degree of association β of cations (M2+) with carboxyl groups of the compounds examined and the single-ion activity coefficients of counterions γM2+. The results were compared with values corresponding to an electrostatic bond of Ca2+ ions to these oligomers. The Cd2+, and especially Cu2+ ions were bound in a considerable measure already to mono- and oligogalacturonates of a low polymerization degree very probably by a chelate bond. Precipitation of Cu- and Cd-oligogalacturonates takes place at a polymerization degree DP 5 and 8, respectively. Interpretation of results by the multiple equilibria theory evidenced that the Cu2+ ions were stoichiometrically bound to mono- and oligogalacturonates (one cation to two carboxyl groups) similarly, as with polymeric D-galacturonan. The results revise the early conception concerning the formation of a positively charged complex of Cu2+ ions (similarly also of Cd2+ and Pb2+ ions) with monogalacturonic acid of (MA)+ type, where A- is the anion of uronic acid. The results are a contribution to the elucidation of the elimination mechanism of these toxic cations from human body involving the oligomeric fragments of pectin as products of its enzymic degradation in the digestive tract.

Influence of Calcium Ions on the Plant Cell Surface: Membrane Fusions and Conformational Changes

1974 ◽  
Vol 32 ◽  
pp. 154-155
Author(s):  
D. James Morré ◽  
Charles E. Bracker ◽  
William J. VanDerWoude
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Conformational Changes ◽  
Calcium Ions ◽  
Surface Membrane ◽  
Carboxyl Groups ◽  
Cross Linking ◽  
Ultrastructural Evidence ◽  
Glycine Max L ◽  
Wall Extensibility

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.

Binding of calcium, lead, and copper(II) cations to galactaric and 2,5-furandicarboxylic acids and to D-galacturonic acid and its derivatives

1986 ◽  
Vol 51 (5) ◽  
pp. 1150-1159 ◽  
Author(s):  
Rudolf Kohn ◽  
Ján Hirsch
Keyword(s):  
Galacturonic Acid ◽  
Uronic Acid ◽  
Indicator Method ◽  
Cu Complex ◽  
Carboxylate Groups ◽  
Counter Ions ◽  
Galactaric Acid ◽  
Furandicarboxylic Acid ◽  
The Difference ◽  
Calcium Lead

The binding of Ca2+, Pb2+, and Cu2+ ions to galactaric and 2,5-furandicarboxylic acids and of Pb2+ and Cu2+ ions to D-galacturonic acid, its α-methylglycoside, and (methyl-4-deoxy-α-D-galactopyranosid)uronic acid was evaluated in terms of the activity coefficients of the counter-ions and the degrees of their association with the carboxylate groups of the acids. The activity of Ca2+ ions was determined by the metallochromic indicator method with tetramethylmurexide, that of Pb2+ and Cu2+ ions, with ion specific electrodes. Galactaric acid bids 89.5% Ca2+ ions, practically all (99.9%) Pb2+ ions and nearly all (98.6% Cu2+ ions, mostly with the formation of insoluble salts. As little as 7.6% Ca2+, 34.0% Pb2+, and 23.9% Cu2+ were bound to 2,5-furandicarboxylic acid in the form of soluble complexes, and slightly more, 4.1% Ca2+, 43.9% Pb2+, and 38.0% Cu2+, to D-galacturonic acid. The difference in the degrees of binding to galactaric acid and 2,5-furandicarboxylic acid is due to the different flexibility of their molecular skeletons. The activities of Pb2+ and Cu2+ ions in solutions of salts of D-galacturonic acid and its derivatives indicate that the OH group at C(4) of D-galacturonic acid takes part in the complexation. For the Pb2+ complex, the OH group at C(1) of the unsubstituted acid in the β-anomeric form also seems to participate in the complexation; this is not the case with the similar Cu complex.

Nitrendipine blocks high potassium contractures but not twitches in rat skeletal muscle

1988 ◽  
Vol 66 (9) ◽  
pp. 1210-1213 ◽  
Author(s):  
G. B. Frank ◽  
L. Konya ◽  
T. Subrahmanyam Sudha
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ions ◽  
Calcium Uptake ◽  
Channel Blocker ◽  
Mechanical Response ◽  
Extracellular Calcium ◽  
The Other ◽  
Rat Skeletal Muscle ◽  
Potassium Depolarization ◽  
High Potassium

The effects of the organic calcium channel blocker nitrendipine was tested on electrically evoked twitches and on potassium depolarization-induced contractures of rat lumbricalis muscles. Nitrendipine (10−7 to 5 × 10−5 M) blocked only the potassium contractures. It was concluded that blocking calcium uptake through the slow voltage-senstitive calcium channels during potassium depolarization blocks the mechanical response of the muscle. Thus extracellular calcium ions are required for the excitation–contraction (E–C) coupling during depolarization contractures. On the other hand, electrically evoked twitches were not affected by nitrendipine; therefore, extracellular calcium ions entering via the slow voltage-sensitive channels are not required for E–C coupling during the twitch.

An Examination of Baker's Acid Haematein Test for Phospholipines

1947 ◽  
Vol s3-88 (4) ◽  
pp. 467-478
Author(s):  
A. J. CAIN
Keyword(s):  
Calcium Ions ◽  
The Other ◽  
Blue Staining ◽  
Other Substances ◽  
Whole Class ◽  
Dark Blue ◽  
General Explanation

1. Baker's acid haematein test for phospholipines is specific provided that only a definite positively result is considered. Very pale blues and greys may be caused by other lipoids, which if present in very large masses may possibly show medium to dark blue granules but will not be coloured all through. 2. The mechanism of the test appears to be as follows: (a) Phospholipine is not fixed by formal-calcium but is restrained from passing into solution by the calcium ions, which play no other part. (b) Phospholipine combines readily with chromium from the mordanting fluid, and is then rendered insoluble and mordanted. Other substances, acidic and usually containing phosphorus, are mordanted as well. (c) On staining, blue and brown colorations are formed; in both cases the dye attaches itself to the chromium in the various substrates. (d) On differentiation, some browns and most blues, particularly those with phosphoric substrates, remain nearly fast, but most browns and the weak blues of certain lipoids (not phospholipines) are greatly reduced or removed entirely. The period of differentiation must not be shortened. (e) Blue-staining lipoids (phospholipines) are distinguished from other blue-staining substances by an extraction with the lipoid solvent pyridine, after special fixation. The other substances, and any bound lipoid not removable with pyridine, remain. 3. Since the specificity of the test depends on the relatively greater affinity of phospholipines among lipoids for the mordant, the period of chroming must not be lengthened. 4. One reason why some substances are coloured after pyridine extraction but not after acid haematein is that in the former case they are precipitated and so concentrated; in the latter they are not. This is not a general explanation for the whole class of such substances.

Bodies of Meaning: Studies on Language, Labor, and Liberation. By David McNally. Albany: State University of New York Press, 2000. 277p. $72.50 cloth, $23.95 paper.

2002 ◽  
Vol 96 (1) ◽  
pp. 189-191
Author(s):  
Nicholas Xenos
Keyword(s):  
New York ◽  
Human Body ◽  
Social Life ◽  
Walter Benjamin ◽  
The Body ◽  
The Other ◽  
State University ◽  
The Real

David McNally styles this book as beginning in a polemic and ending in a “materialist approach to language” much indebted to the German critic Walter Benjamin. The charge is that “postmodernist theory, whether it calls itself poststructuralism, deconstruction or post-Marxism, is constituted by a radical attempt to banish the real human body—the sensate, biocultural, laboring body—from the sphere of language and social life” (p. 1). By treating language as an abstraction, McNally argues, postmodernism constitutes a form of idealism. More than that, it succumbs to and perpetuates the fetishism of commodities disclosed by Marx insofar as it treats the products of human laboring bodies as entities independently of them. Clearly irritated by the claims to radicalism made by those he labels postmodern, McNally thinks he has found their Achilles' heel: “The extra-discursive body, the body that exceeds language and discourse, is the ‘other’ of the new idealism, the entity it seeks to efface in order to bestow absolute sovereignty on language. To acknowledge the centrality of the sensate body to language and society is thus to threaten the whole edifice of postmodernist theory” (p. 2).

Emergence Change of Carbon Dioxide from Artificial Skin by Titania Photocatalyst

2007 ◽  
Vol 544-545 ◽  
pp. 55-58
Author(s):  
Eiji Watanabe ◽  
Mitsuharu Fukaya ◽  
Hiroshi Taoda
Keyword(s):  
Carbon Dioxide ◽  
Visible Light ◽  
Uv Irradiation ◽  
Visible Light Irradiation ◽  
Human Body ◽  
Light Condition ◽  
The Other ◽  
Artificial Skin ◽  
Irradiation Condition ◽  
Titania Photocatalyst

The influence of the titania photocatalyst particle of the nanometer region on the human being and biology’s to be doubted. Removing the uneasiness will expand further uses for the photocatalyst nanoparticle. Then, we attempted to examine the effect of several titania photocatalyst nanoparticles to the artificial skin like the human body under the UV and visible light irradiation conditions. The decomposition degree of the artificial skin was evaluated from the monitoring of the amount of carbon dioxide generated from them by the titania photocatalyst nanoparticle activity. Under the UV irradiation condition, it was almost found the carbon dioxide emergence from the artificial skin by the activity of the titania photocatalyst nanoparticle. On the other hand, under visible light condition it was mostly detected.

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