Amphoteric Properties Research Articles

The Finishing of Wool Tops with Bunte Salt Polyamide Polymers

Hercosett 57 can be readily converted to a Bunte salt terminated polymer which exhibits different ionic character both in solution and at the fibre surface; in alkaline solution it behaves as an anionic polymer, but in weakly acidic solution it possesses amphoteric properties. Because of this overall change in ionic character the polymer can be applied to chlorinated wool tops from baths set at pH 3.5, in marked contrast to Hercosett 57 where bath pH values of 8.0 are required. The dyeing properties of yarns produced from these tops will be described with special emphasis on the differential dyeing possibilities offered by mixing these yarns with the more usual Hercosett 57 treated yarns. Soiling properties of the new finish have also been evaluated.

Interaction of Pb 2+ with hydrous γ-Al 2O 3

Significant adsorption of Pb(II) on to hydrous γ-Al 2O 3 from dilute solutions is observed even at pH values far below the zero point of charge. The specific binding of Pb 2+ on hydrous γ-Al 2O 3 in dilute electrolyte is interpreted as surface complex formation. The amphoteric properties of the coordinating surface are characterized in 0.1 M NaC1O 4 in terms of a two-protic acid-base system (pH ZPC = 8.3). The extent of Pb 2+ interaction with the Al 2O 3 surface was determined both from measurements of residual [Pb 2+] with a Pb 2+ electrode and from the displacement of alkalimetric titration curves by the presence of Pb(II). The complex forming properties of the surface coordination reaction can be quantified by the equilibria: ≡ AlOH + Pb 2+ ⇄ ≡ AlOPb + + H +; 2 ≡ AlOH +Pb 2+ ⇄ (≡ AlO) 2Pb + 2H +. Hydrolysis need not be invoked to describe the interaction.

The use of the amphoteric ion-exchange resin retardion 11A8 for inorganic separations

The use of the “snake in a cage” amphoteric ion-exchange resin Retardion 11A8 for various separations of inorganic ions was investigated. Clean separations of Ga(III)In(III)Tl(III), Pt(II)Pd(II), and Na(I)Ni(II)Cu(II)Zn(II) mixtures have been achieved. In acidic media, in which the resin acts mainly as an anion exchanger, some residual activity of the acrylate polyanion seems to exist, resulting in significant changes in distribution coefficients in comparison with standard anion-exchange resins. In the case of elements that can exist as both cations and anions in solution ( e.g., Ni, Co, Cu and Zn), the amphoteric properties of Retardion 11A8 permit more specific isolation of certain elements from complex mixtures than would be possible with the use of monofunctional ion exchangers.

Ge-doped In xGa 1−xAs p− n junctions

The amphoteric properties of Ge in the In xGa 1−xAscrystals grown by liquid-phase epitaxy are reported. It was found from the Hall measurements that when x < 0·1, the Ge-doped In xGa 1−xAs was p-type, and when x > 0.1,it was n-type . At the vicinity of x = 0.1, therefore, the In xGa 1−xAs p− n junction could be made by one growth process. The electrical and photoelectric characteristics of that junction were investigated. The distribution of Ge concentration at the p− n junction, which was obtained from the C-V characteristics, depended on the doping concentrations of Ge. This dependence can be interpreted by analyzing a modified Longini-Green equation. The spectral responses of both photovoltaic effect and electroluminescence showed that in In 0.1Ga 0.9As, Ge atoms gave rise to a heavy compensation effect, and introduced a conduction band tail of states and two kinds of acceptor levels located ∼ 20and∼ 100meV above the valence band edge.

Specific adsorption of cations on hydrous γ-Al 2O 3

The amphoteric properties of hydrous γ-Al 2O 3 and the distribution of earth alkaline cations in the oxide-electrolyte interface was evaluated from alkalimetric and acidimetric titration curves of aqueous dispersions. In NaCl electrolytes (25°C), pH of zero point of charge is pH zpc = 8.5; acid-base properties can be characterized in terms of a heterogeneous two-protic acid with intrinsic acidity constants p K int 1 = 7.9 and p K int 2 = 9.1. The extent of adsorption of Ca 2+ and other earth alkaline cations on hydrous γ-Al 2O 3 increases with increasing pH; finite adsorption is observed at pH zpc and at pH values slightly lower than pH zpc. Evaluation of adsorption measurements and alkalimetric titration curves indicates that the adsorption of M 2+ can be described by: AlOH + M 2+ ⇄ AlOM + + H +. Operational association constants for this equilibrium were determined; the extent of adsorption increases in the series Mg 2+ > Ca 2+ > Sr 2+ > Ba 2+. In the pH-range above pH zpc, these ions, upon being adsorbed may reverse the surface charge of the oxide suspension.

Amphoteric properties of ge atoms in iny ga1‐y as crystals

Amphoteric properties of ge atoms in in_y ga_1‐y as crystals

Coordination and redox properties in solution

A primitive description of the functional electron cloud is given and is used to account for the mutual influence between coordinating and redox properties. Rules are given for the change in redox properties by coordination and vice versa. It is further shown that the redox potential in a donor solvent is determined by its donor number and an empirical approach is suggested to obtain the electromotive series for any solvent of given donor number. The donor number is also considered important for the ionization of a covalent substrate. Finally a new classification is suggested for charge-transfer complexes. THE PRIMITIVE DESCRIPTION OF THE FUNCTIONAL ELECTRON CLOUD In a primitive way, a characteristic 'electron cloud' may be ascribed to each atom, ion or molecule. Even in the state of highest stability of the entity, the ground state, the electronic arrangement is usually far from 'ideal' as is evidenced by the tendency to undergo chemical reactions. In the primitive description of the 'functional electron cloud', the 'non-ideality' of the cloud is considered responsible for its tendency to change; the actual function will depend also on the properties of the reactant. The functional cloud may deviate from the ideal by being either too 'dilute' or too 'dense' compared with that of the reacting molecule. An entity with a 'dilute' electron cloud will tend to gain electrons or to achieve an appropriate share of them and will thus function as an acceptor of electrons. A system with 'dense' electron cloud will function as a donor of electrons, as it will try to make electrons available. Thus the description emphasizes the actual function of a molecule or ion towards a given reactant and so takes into account amphoteric properties. It has been said that a dense cloud system will function as a donor and a dilute cloud system will function as an acceptor of electrons. Each of these functions may involve either the interaction of an electron pair or the complete exchange of an electron between the reacting species. The interactions of an electron pair donor (EPD or Lewis base) with an electron pair acceptor (EPA or Lewis acid) lead to the formation of a coordinate bond. If an electron is given up completely, the system is regarded as a reducing agent or an electron donor, ED. The oxidizing agent is characterized by accepting the electron and is thus considered the electron acceptor,

Amphoteric Behavior of Bovine Plasma Albumin and Its Detergent Complexes

Abstract Hydrogen ion titration curves have been determined for two stoichiometric albumin-detergent complexes, AD11 and AD76, which are formed through interaction between bovine plasma albumin and the detergent sodium dodecyl benzenesulfonate. The amphoteric properties of the protein moiety in these two complexes have been compared with one another and with those of the uncombined protein. In this analysis, electrophoretic mobility data were used for making the necessary corrections for electrostatic interaction. Tyrosyl ionization curves were established for all three forms by measuring the change with pH of absorption at 295 mµ. The most significant differences found are in the tyrosyl ionization. For albumin itself, the apparent value of pKint is approximately 11.0, and it is concluded that some masked tyrosyl residues are exposed in a cooperative structural change accompanying the ionization. In the case of AD11, tyrosyl ionization is distinctly hypersharp and the apparent pKint is 11.3, implying that in this form the protein is stabilized against unmasking of the tyrosyl residues. In AD76 the apparent pKint is again near 11.0. The titration behavior of imidazole groups is virtually identical in the native protein and in the AD11 complex. In both cases it is necessary to assume two classes of imidazole groups in order to fit the titration curve. In AD76 the titration of these groups can be fitted adequately with a single pKint of 7.30. Surprisingly, very little difference is seen between the various forms in the titration of the e-amino groups. This fact permits the conclusion that electrostatic interaction between the detergent anions and cationic ammonium groups cannot contribute more than 700 cal to the free energy of binding, whereas the total binding free energy (on the unitary scale) must be of the order of 10,000 cal. The fact that the stoichiometry of the complexes is virtually unaltered over the pH range 6.9 to 11.6, over which range the total number of cationic sites in the protein falls from approximately 100 to 40, supports the conclusion that binding is not primarily electrostatic but is probably due to hydrophobic interactions. To a first approximation, all results suggest that the protein in AD11 is essentially in the native state and in fact is stabilized with respect to the structural alteration which must occur on conversion to AD76.

INFLUENCE OF ELECTROLYTES ON STABILITY OF 0.2 MICRON DIAMETER POLYSTYRENE LATEX PARTICLES.

SummaryThe stability of polystyrene latex particles, 2000 A in diameter, in suspension, both uncoated and coated with human gamma globulin, was studied as a function of pH, electrolyte concentration and valence. Uncoated latex particle suspensions became unstable in the presence of polyvalent cations but not anions. When particles were coated with human gamma globulin, they acquired the characteristics of the protein coating, including its amphoteric properties. At pH 5.0 (net charge positive) the presence of polyvalent anions resulted in instability of the coated particles, while at pH 9.0 (net charge negative) the coated particles became unstable in the presence of polyvalent cations.

FORMATE-PYRUVATE EXCHANGE REACTION IN STREPTOCOCCUS FAECALIS. I. FACTOR REQUIREMENT FOR INTACT CELLS.

Wood, N. P. (A. & M. College of Texas, College Station), and D. J. O'Kane. Formate-pyruvate exchange reaction in Streptococcus faecalis. I. Factor requirement for whole cells. J. Bacteriol. 87:97-103. 1964.-A factor present in plant and animal sources was found necessary for the incorporation of formate-C(14) into pyruvate by Streptococcus faecalis 10Cl. Yeast extract produced a response linear in the range between 10 and 30 mg/ml of reaction mixture. Soy peptone, beef peptone, and Brain Heart Infusion replaced yeast extract, but various intermediates, cofactors, amino acids, purines, pyrimidines, and peptides did not stimulate the reaction. A lag occurred in the rate of formate incorporation that was not influenced by anaerobic conditions or growth of cells in a medium containing pyruvate and formate. Phosphate or maleate buffer permitted rapid exchange velocities but tris(hydroxymethyl)aminomethane or collidine buffer was inhibitory. Heating yeast extract at 121 C for 15 min in 3 n H(2)SO(4) produced 66% inactivation of the factor(s), whereas treatment with 3 n KOH produced 97% inactivation. The factor(s) was insoluble in butanol, benzene, ethyl acetate, or chloroform. The material adsorbed on Dowex-1 (OH(-)) and Amberlite IR-120 (H(+)) but not on Amberlite IR-4B (OH(-)). The active component(s) was highly polar, nonvolatile, dialyzable, and had amphoteric properties.

Studies on the Amphoteric Properties of Taka-amylase A

Journal Article Studies on the Amphoteric Properties of Taka-amylase A: II. Unmasking of Acid Binding Sites* Get access TOSHIO TAKAGI, TOSHIO TAKAGI From the Department of Biology, Faculty of Science and the Division of Physical Chemistry, Institute for Protein Research, Osaka UniversityOsaka Search for other works by this author on: Oxford Academic PubMed Google Scholar TOSHIZO ISEMURA TOSHIZO ISEMURA From the Department of Biology, Faculty of Science and the Division of Physical Chemistry, Institute for Protein Research, Osaka UniversityOsaka Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Biochemistry, Volume 49, Issue 1, January 1961, Pages 43–48, https://doi.org/10.1093/oxfordjournals.jbchem.a127251 Published: 01 January 1961 Article history Received: 21 July 1960 Published: 01 January 1961

Tripyridyl carbinols: A group of tertiary alcohols with amphoteric properties: 104th Communication on pyridine derivatives

AbstractThe synthesis of five new tripyridyl carbinols is described, so that seven out of the ten possible isomers of this group are now known. The tripyridyl carbinols are not only weak bases, they show also the properties of very weak acids; the acid dissociation constants are of the order of magnitude of 10−12 to 10−14 and were determined from the relationship between the solubility in dilute alkali and the hydroxyl‐ion concentration. The connection between structure and acid properties is discussed.

The Application of Radiochemical Techniques to the Study of the Interaction of Hair Fibers with Aqueous Solutions

Radioactive tracer techniques have proved to be uniquely adaptable to the study of the inter action of hair fibers with various aqueous solutions including dye baths. NaBr solutions, NaBr- HBr solutions, NaCl solutions, and an acid dye bath containing a sulfur-labelled acid dye for wool were used. It was found that appreciable amounts of NaBr were absorbed by hair from solution with a linear relationship existing between the equilibrium amount absorbed and the molarity of the treating solution. If acidic or basic solutions were used, additional absorption resulting from the well-known amphoteric properties of keratin was observed. In a preliminary experiment, the absorption of each of three componen's of an acid dye bath was followed by taking advantage of differences in radioactive behavior of the three species. Certain rate processes have also been followed.

Mode of action of beryllium on alkaline phosphatase.

RECENTLY, Klemperer et al. 1 and Grier et al. 2 demonstrated the inhibitory effect of low concentrations of beryllium salts on alkaline phosphatase in vitro. This action was found to be rather specific3 and we hoped to be able to shed new light on the old controversy concerning intestinal sugar absorption4,5 and the role of alkaline phosphatase. Into isolated parts of the rat's small intestine, left in situ, we introduced solutions of glucose with or without added beryllium sulphate. There was no difference in the rate of absorption of glucose. Any conclusion from these experiments, however, is dependent on whether the phosphatase is inhibited in vivo as it is in vitro. Klemperer3 suggested that interference with phosphatase action is related to the toxicity of beryllium. This would include an action on phosphatase in vivo. It seemed necessary, however, to obtain more conclusive evidence about this problem, especially about the mode of action of beryllium salts on alkaline phosphatase. Klemperer et al. 1 and Grier et al. 2 considered the possibility that, owing to the amphoteric properties of beryllium hydroxide, beryllate ions might be the inhibiting agent at the pH of optimal enzyme activity. We confirmed the observation of the first-named authors that the relative inhibition increases with increasing pH, reaching a constant high value at the pH of optimal enzyme activity; but we must agree with them that no conclusion can be drawn therefrom as to the form in which beryllium is active as an inhibitor. Treadwell and Boner6, however, clearly demonstrated that beryllate ions do not exist at a pH lower than 12.5. At the pH of optimal enzyme activity (9.6) practically all the beryllium will be in the form of precipitated (colloidal) beryllium hydroxide.

On the mechanism of enzyme action. LIII. The amphoteric properties of trypsin

Several methods were employed for the preparation of salt-free trypsin samples which were used to determine the electrometric titration curves of the enzyme. These curves point to a maximum acid-binding capacity below pH 2. Stoichiometric analysis indicates the presence of 6 carboxyl groups per 10,000 g. of proteins, 1 imidazole group, and 13 hydroxyl-binding groups. Calcium has a specific effect on the titration curves by increasing the acidity of the carboxyl groups in the pH range 3.5 – 5. This effect is not shown by potassium, sodium, or even the bivalent magnesium ion. It is attributed to the formation of a specific complex between the enzyme and the calcium ions, involving the carboxyl groups of the protein. The equally specific protective effect of calcium on the self-digestion of trypsin can therefore be explained by assuming the formation of a complex which stabilizes the enzyme. There is good qualitative agreement between the pH dependence of the electrophoretic mobility of the enzyme and the titration curves. In addition to stabilizing the enzyme, calcium also slightly increases its activity. The investigation of the dependence of the proteolytic activity of trypsin on the pH in the presence or absence of calcium at various temperatures indicates that both effects of calcium ions, the protective effect and the increase in activity, are due to a shift of the equilibrium between native and denatured enzyme in favor of the active form.

150. Studies on some metal electrodes. Part V. The amphoteric properties of antimony tri- and pent-oxide

150. Studies on some metal electrodes. Part V. The amphoteric properties of antimony tri- and pent-oxide

Relationships of Ampholytes to Assimilation and Recovery of Ammonium and Nitrate Nitrogen in Plant Tissue

Data are presented which show that nitrate and ammonium ions may not be recovered from living tissue in absolute amounts. This results from the fact that protoplasm contains proteins and amino acids which have amphoteric properties and which form dissociation compounds with nitrate and ammonium ions which obey the laws of electrochemistry. The conditions in cells necessary to support the above assumption are suggested, together with an explanation of conditions which favor nitrogen assimilation and subsequent growth in plants.

THE INFLUENCE OF pH ON THE MOBILITY AND DIFFUSION OF OVALBUMIN

Annals of the New York Academy of SciencesVolume 41, Issue 4 p. 267-286 THE INFLUENCE OF pH ON THE MOBILITY AND DIFFUSION OF OVALBUMIN L. G. Longsworth, L. G. Longsworth From the Laboratories of The Rockefeller Institute for Medical Research New York City, New YorkSearch for more papers by this author L. G. Longsworth, L. G. Longsworth From the Laboratories of The Rockefeller Institute for Medical Research New York City, New YorkSearch for more papers by this author First published: July 1941 https://doi.org/10.1111/j.1749-6632.1941.tb35242.xCitations: 99AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume41, Issue4The Amphoteric Properties of ProteinsJuly 1941Pages 267-286 RelatedInformation

Conference of “The Amphoteric Properties of Proteins”

Conference of “The Amphoteric Properties of Proteins”

Chemical Studies on the Components of Normal and Neoplastic Tissues III. The Composition and Amphoteric Properties of the Nucleoprotein Fraction of the Jensen Rat Sarcoma

Journal Article Chemical Studies on the Components of Normal and Neoplastic Tissues III. The Composition and Amphoteric Properties of the Nucleoprotein Fraction of the Jensen Rat Sarcoma Get access Jesse P. Greenstein, Jesse P. Greenstein research fellow National Cancer Institute, National Institute of Health, United States Public Health Service Search for other works by this author on: Oxford Academic PubMed Google Scholar J. W. Thompson, J. W. Thompson associate pharmacologist National Cancer Institute, National Institute of Health, United States Public Health Service Search for other works by this author on: Oxford Academic PubMed Google Scholar Wendell V. Jenrette Wendell V. Jenrette junior physiologist National Cancer Institute, National Institute of Health, United States Public Health Service Search for other works by this author on: Oxford Academic PubMed Google Scholar JNCI: Journal of the National Cancer Institute, Volume 1, Issue 3, December 1940, Pages 367–376, https://doi.org/10.1093/jnci/1.3.367 Published: 01 December 1940