Neutral Salt Solutions Research Articles

A Comparison of Proteinpolysaccharides of Bovine Nasal Cartilage Isolated and Fractionated by Different Methods

Abstract Crude proteinpolysaccharide extractable by three fundamentally different methods, called mild, disruptive, and dissociative, has been separated into the same series of three significantly distinct fractions by a method capable of operating with gram quantities involving differential ultracentrifugation in neutral salt solutions at high concentrations. The three fractions separated by this method following dissociative extraction with 3 m MgCl2 have been related by their analytical and sedimentation properties to fractions prepared by different methods in two other laboratories. The fraction smallest in size, called PPL3, has a molecular weight of 2.4 x 106 and accounts for 25 to 49% of the crude product extracted. The fraction next larger in molecular weight, called PPL5, amounts to 30 to 50% of the crude product extracted. PPL6, the most rapidly sedimenting fraction, amounts to 5% of the crude product and contains 0.6% hydroxyproline. PPL3 and PPL5, the two components accounting for 70% of the crude proteinpolysaccharide, are clearly demonstrable in sedimentation velocity studies on crude proteinpolysaccharide only at low concentration (l2.5 mg per ml). At higher concentrations (g4 mg per ml), convergence of the sedimentation coefficients of the two components and a marked Johnston-Ogston effect produce a single hypersharp boundary, obscuring the presence of two components in crude proteinpolysaccharide. This may account for the conclusion of some workers that proteinpolysaccharides from bovine nasal cartilage contain a single major component.

Some Folists on Whiteface Mountain, New York

AbstractRelatively shallow, nonsaturated organic soils on Whiteface Mountain in New York have been characterized and classified. These Folists consist of strongly acid O1 and O2 horizons of litter accumulations in varying stages of decomposition overlying bedrock or carpeting fragmental materials at depths commonly ranging from 10 to 75 cm. These soils occur mainly above 760‐m elevation and are relatively pure units on narrow ridge crests and on steep mountain slopes. On less steep slopes these Folists are intimately associated with Spodosols. The main families observed are: dysic Typic Borofolists; dysic, micro‐Typic Borofolists; dysic Lithic Borofolists; dysic, shallow Lithic Borofolists; and dysic, micro Lithic Borofolists. Borofolists are cold Folists with mean annual soil temperature < 8C; the Lithic subgroups have a lithic contact within 1 m of the surface; and the Typic subgroups are underlain by fragmental materials. The shallow family indicates a lithic contact between 18 and 50 cm, whereas the micro family has a solum less than 18 cm thick. All families observed are dysic having a pH < 4.5 measured in neutral salt solution.

ON THE NATURE OF ALTERED PROTEIN IN COD MUSCLE STORED AT −29°C AFTER AGING IN ICE

SUMMARYAdditional protein, inextractable with the usual technique, was extracted from cod muscle which had various free fatty acid contents and had been stored at −29°C after aging in ice. Ultracentrifugal patterns showed that the extracted protein was aggregated and polydisperse. Sedimentation behavior was similar to that of aggregated protein in extracts of muscle in which protein‐free fatty acid interaction occurred during prolonged aging in ice. Conditions under which altered protein was extracted, overnight exposure of homogenized muscle to neutral salt solution followed by rehomogenization; phase contrast micrographs of residues of homogenates before and after rehomogenization; and ultracentrifugal patterns of extracts containing aggregated protein that had been stored in extractant suggested that some of the linkages resulting from reactions in the frozen state were salt‐sensitive. The association that occurred in the muscle after storage at −29°C appeared to be more stable in a neutral salt environment than that occurring in muscle aged in ice.

The Osmotic Pressure of Polyelectrolyte in Neutral Salt Solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Osmotic Pressure of Polyelectrolyte in Neutral Salt SolutionsAkira Takahashi, Narundo Kato, and Mitsuru NagasawaCite this: J. Phys. Chem. 1970, 74, 4, 944–946Publication Date (Print):February 1, 1970Publication History Published online1 May 2002Published inissue 1 February 1970https://doi.org/10.1021/j100699a048RIGHTS & PERMISSIONSArticle Views408Altmetric-Citations70LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (346 KB) Get e-Alerts

The behaviour of cation-exchange thin layers with alkaline and neutral salt solution as eluents

The behaviour of weak and strong ion exchangers in the sodium salt form is studied using neutral solutions of uni- and divalent ions and alkaline solutions of univalent ions as eluents. The influence of various parameters (rate of exchange reaction, diffusion rate, swelling capacity, etc.) on the chromatographic behaviour of the ions has been investigated. The conditions for the determination of ionic charge and the selectivity coefficients of the exchangers for some univalent and divalent ions are given.

Conductometric and Potentiometric Titration of Exchangeable Aluminum

AbstractConductometric and potentiometric titrations of an AlCl3 solution and AlCl3‐treated Dowex‐50, trioctahedral vermiculite, and two montmorillonites were compared with the Al and acidity removed from these systems with neutral chloride salts. The endpoints of potentiometric titrations of AlCl3 or AlCl3‐treated exchangers in neutral salt solution were lowered by these salts and adsorption of partially neutralized hydroxy‐Al groups on the exchangers. Titrations of solutions to pH 8.0 gave better estimates of the acidity present than did inflection points. Hydrolysis of Al on the exchanger during exchange may produce H+ ions not originally present. Conductometric titrations with Na2B4O7 and NaOH were confounded by incomplete exchange and reaction with Al. The formation of aluminate in the titration with NaOH and Ba(OH)2 decreased the conductivity and caused “high” results. It is proposed that conductometric titrations should be continued until the change in conductivity with added base approaches that of a blank. A method for correcting for aluminate formation is proposed.

Variations in some physicochemical properties of collagen with age.

By use of extraction with neutral salt solutions and acidic solutions of graded ionic strength, purified soluble collagens were obtained from the skins of 1-day-old and 2-year-old rats. The extracted collagens of 1-day-old rats did not differ significantly from those of 2-year-old rats with respect to denaturation temperature, viscosity, or sedimentation velocity. However, collagens obtained from the older as compared with the younger animals did have lesser contents of tyrosine, hexoses, and aldehydes. Contents of ester-like bonds and amino acid composition did not differ in the corresponding collagens of 1-day-old and 2-year-old rats. Significantly, there was a difference in degree of intramolecular crosslinkage between corresponding collagens of young and older rats as demonstrated by the larger contents of β components in the collagens of the 2-year-old animals.

In vitro formation of intramolecular crosslinks in tropocollagen

Administration of penicillamine (β,β, dimethyl cysteine) to rats causes a disturbance of collagen metabolism that resembles lathyrism (Nimni and Bavetta, 1965). The neutral salt soluble collagen which accumulates in rats treated with penicillamine consists almost exclusively of α components (Nimni, 1965), but once extracted from tissues and purified, it forms stable fibers at 37°C ( Deshmukh and Nimni, 1969a). This contrasts with lathyritic collagen which forms unstable fibers that redissolve in cold neutral salt solutions ( Gross, 1963). This fundamental difference in behavior suggested that the soluble collagen extracted from the penicillamine treated animals should be capable of generating stable intramolecular as well as intermolecular crosslinks. The present communication describes the formation of intramolecular crosslinks in vitro , which in turn, suggests a suitable model for the further study of the biosynthesis and characterization of this type of crosslink.

Coulometric titration of bases in concentrated neutral salt solutions in water and non-aqueous solvents

Weak bases were titrated with coulometrically generated hydrogen ions in aqueous 8 M sodium perchlorate solutions. Bases with ionization constants as low as 4·10 -12 were titrated in acetone containing 3 M lithium perchlorate. Enhancement of end-point breaks was obtained in both solvents in the presence of the concentrated salts. Methods of end-point detection were investigated.

A specific soluble protein from the catecholamine storage vesicles of bovine adrenal medulla II. Physical characterization

50% of the soluble protein of the chromaffin granules consists of a homogeneous protein. The protein has a molecular weight of 81 200 in neutral salt solutions as measured by rapid equilibrium osmometry. Molecular weight measurement by sedimentation equilibrium in 6 M guanidine·HCl with a reducing agent present shows that the protein is composed of two identical or nearly identical subunits of weight average mol. wt. 40 600. The protein is partially randomized at neutral pH at both ionic strengths 0.03 and 0.3, as indicated by a marked dependence of the sedimentation coefficient on protein concentration. However, at ionic strength 0.3, as the pH approaches the isoelectric pH (4.5), the protein is more compact and behaves in an almost globular manner.

Chemical changes associated with aging of collagen in vivo and in vitro.

Collagen extracted from rat skin by neutral-salt solutions contains less aldehydes than the more insoluble collagen fractions. The concentration of aldehydes in collagen is directly related to its capacity to form stable cross-linked gels, which do not redissolve on cooling and become more insoluble in a variety of reagents. Whereas the absorption spectrum of neutral-salt-soluble collagen treated with N-methylbenzothiazolone hydrazone resembles that of acetaldehyde, the more insoluble collagen fractions show increasing amounts of a component that behaves like an alphabeta-unsaturated aldehyde. The ratio between alpha- and beta-sub-units present in a particular fraction of soluble collagen seems to be constant and independent of the age of the animal. Neutral-salt-soluble collagen, which has a low concentration of beta-components, will generate intramolecular bonds if gelled at 37 degrees . These intramolecular bonds seem to precede the formation of stable intermolecular cross-links, since these gels can redissolve when cooled to yield a soluble collagen with a higher content of beta-components of intramolecular origin.

Solubility of collagen fibrils formed in vitro in the presence of sulphated acid mucopolysaccharide-protein.

THE results of many investigations1,2 have indicated that tropocollagen molecules are capable of self-assembly into “native-type” fibrils when highly purified collagen solutions are incubated at 37° C. The insolubility of these fibres in cold neutral salt or acidic solutions increases, with the length of time of prior incubation at 37° C, and Gross3 has concluded that the molecular components of the fibrils acquire a more closely packed alignment, facilitating the formation of numerous non-covalent bonds. I have found in previous studies4,5 that certain sulphated acid mucopolysaccharide (AMPS)-proteins interact with tropocollagen to form characteristic fibrous precipitates. I have investigated the possibility that this interaction may also give rise to collagen fibres of increased insolubility.

A study of the hydrogen ion concentration gradient on alginic acid thin layers

The various types of hydrogen ion concentration gradients formed along a chromatographic layer during elution with mineral acids, buffer solutions, and neutral salt solutions were thoroughly investigated. The results indicate that the formation of such gradients may be attributed to a process of absorption by the substrate and to ion-exchange. Various analytical applications are envisaged.

Relation between Protein Extractability and Free Fatty Acid Production in Cod Muscle Aged in Ice

Protein extractability decreased as free fatty acid (FFA) was produced in cod muscle aged in ice. The decrease was small compared with that occurring in frozen-stored muscle of similar FFA content. Prolonged extraction in neutral salt solution in the presence and absence of bovine serum albumin (BSA) showed that loss in protein extractability in muscle aged in ice was reversible through dissociation of inextractable material and that the presence of BSA, a FFA acceptor, favored greater dissociation. Ultracentrifugal patterns of protein extracted from ageing muscle showed increasing polydispersity. Phase contrast microscopy showed that the inextractable material contained muscle fragments consisting of bundles of myofibrils, some of full fiber width. These results indicate that in ageing muscle, interaction of contractile protein with FFA results in the formation of a cross-linking network within the muscle fiber causing resistance to fragmentation and to protein extractability, and that the observed smaller loss during ageing in ice is in part due to dissociation occurring during extraction. They suggest that in muscle aged in the frozen state, the reaction between contractile protein and FFA increases and the complexes formed are stabilized.

The reflection of the age, tissue and solubility on the Amberlite CG-50 fractions of denatured collagens.

AbstractCollagen was extracted and purified from the skins of young and full‐grown guinea pigs and from the skins and tendons of calf and cow, first with neutral salt solutions and acidic buffers in the cold and then the residue was gelatinized by stepwise heating. In the young animals the collagenous material which could be solubilized at +65°C already was increased markedly. The various denatured collagens were fractionated with Amberlite CG‐50 columns, eluted with buffers of increasing ionic strength and pH and finally with sodium hydroxide. The first fraction, emerging at pH 5.50, was large in the samples from soluble collagen (in comparison to insoluble), in the extracts from insoluble collagens of young animals (in comparison to adults) and in the collagenous fractions of tendon (in comparison to the skin). The gradient‐buffer‐eluted fraction which had been derived from insoluble collagen at progressively raised temperatures contained in abundance imino acids and hydroxy amino acids (in comparison to soluble collagens).

The Reflection of the Age, Tissue and Solubility on the Amberlite CG‐50 Fractions of Denatured Collagens

AbstractCollagen was extracted and purified from the skins of young and full‐grown guinea pigs and from the skins and tendons of calf and cow, first with neutral salt solutions and acidic buffers in the cold and then the residue was gelatinized by stepwise heating. In the young animals the collagenous material which could be solubilized at +65° C already was increased markedly. The various denatured collagens were fractionated with Amberlite CG‐50 columns, eluted with buffers of increasing ionic strength and pH and finally with sodium hydroxide. The first fraction, emerging at pH 5.50, was large in the samples from soluble collagen (in comparison to insoluble), in the extracts from insoluble collagens of young animals (in comparison to adults) and in the collagenous fractions of tendon (in comparison to the skin). The gradientbuffer‐eluted fraction which had been derived from insoluble collagen at progressively raised temperatures contained in abundance imino acids and hydroxy amino acids (in comparison to soluble collagens).

Heterogeneity of Montmorillonite Surface and Its Effect on the Nature of Hydroxy-Aluminum Interlayers

AbstractA specimen montmorillonite (Arizona bentonite) was treated with hydroxy-aluminum solutions of various basicity. The cation exchange sites of this clay were found not to be homogeneous in their strength of retaining hydroxy-aluminum polymers; this strength varied from very weak, with which the Al polymers were only loosely held, to very strong, with which stable interlayer Al-clay complexes were formed. When a large amount of clay was treated with a small amount of solution, the polymers were held only in positions of strong affinity; the polymers were difficult to extract with neutral salt solutions and did not change to crystalline Al(OH)3 during prolonged aging. When a small amount of clay was treated with a large amount of solution, the exchange sites were completely occupied by polymers; a portion of these polymers was easily extractable with neutral salt solutions and, during aging, changed to Al(OH)3. This contrast is significant in any attempt to compare results obtained under different experimental conditions and to correlate laboratory experimentation with the occurrence of gibbsite and interlayer Al-clay complexes in nature.

Intermolecular Relationship between Neutral-salt-soluble and Acid-soluble Collagen

SOLUBLE collagen can be extracted from collagenous material with neutral salt solutions and weak acids. These extracts display many similar physical and chemical characteristics, but differ significantly with respect to their solubility. Neutral-salt-soluble collagen has been shown to be the precursor collagen1,2, with acid-soluble collagen being the more mature fibre-forming protein3. The relationship between these soluble collagens which is usually accepted relies on the presence or absence of intramolecular cross links. Apart from hydrogen bonds no intramolecular bonds are considered to occur in neutral-salt-soluble collagen. On the other hand, acid-soluble collagen is formed as intramolecular bonds are introduced into neutral-salt-soluble collagen. Such a relationship alone is insufficient, however, to explain the very different solubility properties of these two forms of collagen. It is therefore proposed that neutral-salt-soluble and acid-soluble collagen are related on an intermolecular basis in their native environment, but that their subsequent extraction in mildly acid and basic conditions results in the degradation of terminally located telopeptides, which play a vital part in the properties of these collagen preparations. The evidence for this theory is now outlined.

Black lipid membranes in aqueous media: The effect of salts on electrical properties

The electrical properties of black lipid membranes of about 50A in thickness have been studied. The arrangement used consisted of the following: calomel electrode/aqueous solution/black lipid membrane on Teflon support/aqueous solution/calomel electrode. The membranes were generated from freshly recrystallized cholesterol and n-dodecane in an aqueous medium containing hexadecyltrimethylammonium bromide (HDTAB). Measurements of interfacial tension on these bimolecular membranes have been made with a modified maximum bubble pressure method. The interfacial tensions of the membrane formed in HDTAB-H 2O and HDTAB-0.1 M NaCl solution were, respectively, 0.65 and 0.15 dyne/cm. The crucial role played by surface-active compounds with regard both to membrane formation and stability is briefly discussed. Electrical properties of these ultrathin membranes were investigated in the presence of various solutions of neutral salts (pH 6.85–6.95). In dilute solutions (10 −4or 10 −3 M) the resistance of the membrane was 10 7–10 8 ohms-cm. 2. Further, it has been found that the transverse membrane resistance is dependent both on the electrolyte concentration and the anionic species used. For most electrolytes studied, the d.c. membrane resistance decreased by several orders of magnitude when the concentration was about 0.01 M. The order of specific effect of anions in lowering membrane resistance has been found to be I − > Br − > SO 4 −2 > Cl − > F −. The observed effect is discussed qualitatively in terms of the interaction between the quaternary ammonium groups and anionic species at the membrane-water interface. The membrane capacitances were obtained by a d.c. transient method, which showed significant variations when salt concentration or species was altered. The values of the capacitance ranged from 0.7 to 1.1 μf.cm. 2. The observed variations are considered in terms of the electrical double layer capacitances at the membrane-solution interfaces.

Influence of Concentrated Neutral Salt Solutions on the Corrosion of Metals

The H+ activity of diluted strong acids, such as or , rises by the addition of such neutral salts as , from 10−1 to 10 at constant concentration of the acid. The effect of this increase of activity on the anodic dissolution of Fe, Co, and Ni has been investigated. Fe and Co show the order with respect to the H+ activity, which was found by many other authors with respect to the H+ concentration when stationary measurements were accomplished. In accordance with the Heusler mechanism the order changed to at unstationary measurements. The cathodic process has the order with respect to the H+ concentration and 0.5 with regard to H+ activity changed by addition of neutral salts. The anodic dissolution is influenced by the nature of the cations .On the contrary the order of anodic dissolution of Ni is with regard to H+ concentration as well as to activity both at stationary and unstationary measurements. The cathodic process at Ni has the order with regard to H+ concentration and 0.5 with regard to H+ activity changed by addition of neutral salts. At the hydrogen ion discharge on the mercury electrode the order of reaction with regard to H+ concentration rises from 0.5 to 1 with increasing ionic strength according to the theory of Frumkin. The dependence upon at constant H+ concentration is complicated. The current density at constant potential passes through a maximum with increasing H+ activity and content of neutral salt. Height and position of this maximum with regard to the neutral salt concentration depend on the potential. A qualitative interpretation of the experimental results is proposed.