Relative affinities of the anions of strong acids for wool protein

Steinhardt, Jacinto; Fugitt, Charles H.; Harris, M.

doi:10.6028/jres.026.017

Cited by 72 publications

(10 citation statements)

References 21 publications

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“…Under ordinary conditions, amide and peptide groups are too weakly basIc to combine to any appreciable extent with hydrogen ions at these concentratIOns of acid, but their readiness to combine with hydrogen ions may be greatly increased by acquiring a negative charge by combination with an anion. SImilar effects of charge on the strengths of acids and bases have been discussed by the present authors [8,9] and have been treated theoretically by many others. The fact that much more hydrogen ion than dodecylsulfonate ion must be present to attain the maximum rate of amide hydrolysis mdicates that the proteins com bine with hydrogen ion less readily than with dodecylsulfonate.…”

Section: Mechanism Of the Cat Al Ysismentioning

confidence: 94%

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Catalyzed hydrolysis of amide and peptide bonds in proteins

Steinhardt¹,

Fugitt²

1942

J. RES. NATL. BUR. STAN.

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The rates of hydrolysis by dilute acids of both a dissolved protein (egg albumin) and an insoluble protein (wool) are shown to depend not only on the temperature and acidity but also on t he acid used. When hydrolyzed at 65° C by certain strong monobasic acids of high molecular weight, the amide and the peptide bonds are broken over 100 times as fast as when they are hydrolyzed with hydrochloric acid. Even among the common mineral acids, large differences appear. These differences in hydrolytic effectiveness parallel differences in the affinities of the anions of the acids for protein. A further reason for attributing t his effect to the anions is the attainment, with anions of high affinity, of a maximum rate of amide hydrolysis at r elatively low concentrations, stoichiometrically equivalent to the sum of the amino plus the amide groups. A similar limiting anion concentration or maximum rate of hydrolysis of t he much more numerous peptide groups is not observed. On the basis of details of t he dependence of the rate of hydrolysis on concentration of effective anions and hydrogen ions, a m echanism which involves combination of the groups hydrolyzed with hydrogen ions, is proposed.At low concentrations of effective anions, amide hydrolysis is catalyzed more strongly than peptide hydrolysis. By keeping the concentration slightly below stoichiometric equivalence to the sum of the amino plus amide groups the amide groups may be rapidly hydrolyzed without extensive hydrolysis of the peptide bonds in the protein. Practical applications are suggested.

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Section: Mechanism Of the Cat Al Ysismentioning

confidence: 94%

“…Details of the purification of both proteins and, with few exceptions,4 of the reagents used, have been described elsewhere [8,9]. The kinetic procedures were as follows:…”

Section: Experimental Procedures 1 Experimental Conditionsmentioning

confidence: 99%

Catalyzed hydrolysis of amide and peptide bonds in proteins

Steinhardt¹,

Fugitt²

1942

J. RES. NATL. BUR. STAN.

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“…* Steinhardt ct al. [11] demonstrate in their work on the absorption of different strong acids that the character of the anion and its molecular weight is essential for the amount of uptake. Correspondingly, it is to be supposed in our case, too, that the tenside anion influences the absorption.…”

Section: Acknowledgmentmentioning

confidence: 99%

Influence of Tensides on the Mechanical and Absorption Properties of Wool Fibers

Zahn

Stein

Blankenburg

1967

Textile Research Journal

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“…It has been found possible to correlate the observed titration curves of soluble proteins with their amino-acid content [5.]. [20,28]. (Points: electrokinetic; continuous curves: acid combination.…”

Section: Structure Of the Wool Fibermentioning

confidence: 99%

“…Theoretical and experimental acid-binding curves at diff erert ionic strengths for wool. Points experimental [28] ; cUr¿'es calculated from theory of Gilbert and Rideal [9], fitted at one point only and corrected for activity coefficients of claloride ion.…”

Section: Difference Between Soluble and Insoluble Proteinsmentioning

confidence: 99%

The Role of the Electric Double Layer in the Sorption of Acids and Dyes by Wool

Alexander¹,

Kitchener

1950

Textile Research Journal

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a g g e r ;THE LITERATURE concerning the combination of textile fibers with acids and dyes shows that, although a considerable amount of reliable data are available, the subject is in a confused state: numerous apparent discrepancies exist and no clear explanation has been given for the wide variety of observed effects. It is the purpose of this paper to show that the whole range of the phenomena concerned can be satisfactorily accounted for in terms of accepted concepts of the structure of electrical double layers. The argument will be developed with reference to wool, but it will be a simple matter to extend it to other fibers. Structure of the Wool FiberModern optical and electron-microscopic work [30~ has proved that wool has a complex morphological structure comprising exterior scales, an underlying thin membrane [14], interior elongated cortical cells, and microfibrils connected together by amorphous material. Although the scales obstruct the entry of dyes [2 7 ~ and contain a somewhat greater proportion of cystine [8~, they show electrophoretic behavior identical with that of the cortical cells [20]. For the present purpose, it is not necessary to take the morphological structure into account and the wet fiber may be regarded simply as an infinite homogeneous cylinder having molecular channels of relatively large dimensions, the existence of which is amply proved by the ability of large molecules to penetrate into the fiber.The polypeptide chains with their variety of side chains, having inter alia -NH2 and -COOH groups, are held in position by hydrogen bonds [3ã nd disulfide links. There can be no doubt from the clear findings of Speakman [24~ on the mechanical properties of wool as a function of pH that at the isoelectric point of the wool (defined by zero electrokinetic potential) the amino and carboxyl 1 groups exist largely in the zwitterion condition, -NH3+...-OOC-. The fact that addition of neutral salts has no influence on the extensibility [25~ proves that the two groups are very close together, forming the so-called &dquo;salt link,&dquo; which may be pictured as a dipole. It is, perhaps, more than a coincidence of nature that the amino and carboxyl groups are present in equal numbersapproximately 0.8-0.9 equivalents per kg. of drv wool. X-ray diffraction patterns of wool fibers show that their degree of crystallinity is appreciable [2~.

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Relative affinities of the anions of strong acids for wool protein

Cited by 72 publications

References 21 publications

Catalyzed hydrolysis of amide and peptide bonds in proteins

Catalyzed hydrolysis of amide and peptide bonds in proteins

Influence of Tensides on the Mechanical and Absorption Properties of Wool Fibers

The Role of the Electric Double Layer in the Sorption of Acids and Dyes by Wool

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