The action of sulphites on the cystine disulphide linkages of wool

Middlebrook, W. R.; Phillips, Henry

doi:10.1042/bj0360428

Cited by 45 publications

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“…effect on the cystine links. The nomenclature .~, B, C, and D for the cystine fractions is that of Middlebrook and Phillips [25]. The following comments provide additional information to Table I.…”

Section: Methodsmentioning

confidence: 99%

“…It is (ii'ffictilt at present to see how direct evidence for this suggestion can be obtained, but it has long been a tenet of polymer chemistry that macroscopic elastic properties can ---,-, be related to molecular structure. Accordingly, an investigation of the alteration in elastic properties of wool fibers produced by systematic variation of the number and kind of disulfide bonds [25] was undertaken, and this paper records the results.…”

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confidence: 99%

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The Elastic Properties of Chemically Modified Wools and Their Implications for Theories of Wool Structure

Lindley¹

1957

Textile Research Journal

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

The Elastic Properties of Chemically Modified Wools and Their Implications for Theories of Wool Structure

Lindley¹

1957

Textile Research Journal

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“…Information was also sought regarding the environment of disulphide bonds in wool. Since only about half the -S-8-bonds in some types of wool are readily reduced (Middlebrook and Phillips 1942), and since it is possible to label reduction sites by means of [14C]iodoacetate (Gillespie and Springell 1961;Springell et al 1964), it became feasible to determine whether the bonds nearby the more labile -8-S-bonds were also the most susceptible to proteolysi~.…”

Section: Introductionmentioning

confidence: 99%

Proteolysis of Wool and its S-Carboxymethyl Derivatives by Pronase and Other Proteases

Springell¹

1963

Aust. Jnl. Of Bio. Sci.

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SummaryThe proteolysis of native Merino wool by pronase, a protease from Streptomyces griMm, was shown to resemble that of other proteases in liberating cortioal cells and solubilizing less than 20% of the fibre.The action of proteases on fully reduced and alkylated wool and on soluble wool proteins was compared. Modified whole wool was digested most rapidly by pronase and the least readily by pepsin. (3.4.4.1). High.sulphur proteins extracted from wool were broken down by pepsin initially at least 10 times faster than the low-sulphur proteins. The structural significance is discussed.An attempt was made to determine whether peptide bonds in the vicinity of the more readily reducible disulphide bonds were the most susceptible to proteolysis. Varying proportions of the carboxymethyl groups of fully reduced and alkylated preparations were labelled with 14C. The release of trichloroacetic acid-soluble 14C and nitrogen was measured after varying periods of incubation with proteases. The rate of liberation of 14C from modified whole wool by pronase and trypsin (3.4.4.4) was independent of the proportion of 14C present in the preparations. With pepsin, the 14C release was variable, but the ratio of percentage 14C release to percentage nitrogen release was constant and thus not related to the proportion of labelled S·carboxymethyl groups present. The rate of production of 14C soluble in trichloroacetic acid from the high-sulphur proteins was also independent of the proportion of 14C label present. The more easily reducible portion of the low-sulphur proteins appeared to be somewhat more resistant to proteolysis than the rest of the molecule, but when the nitrogen liberation was taken into account, a lack of dependence on the 14C content could once again be demonstrated.These and other findings are consistent with a random distribution of the more easily reducible disulpbide bonds in the wool fibre.

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“…The changes in the elastic properties of wool, brought about by different reagents, are mainly due to the breaking of these disulfide crosslinkages. ' If wool is treated with sodium bisulfite, according to Clarke [5] and Speakman [17], the combined cystine undergoes the following reaction: In 1946, Carter, Middlebrook, and Phillips [4] summarized the results of previous investigations [7,8,12]. They came to the conclusion that not all of the combined cystine reacts in the same way with sodium bisulfite, but that cystine can be divided into different fractions.…”

mentioning

confidence: 99%

“…In 1946, Carter, Middlebrook, and Phillips [4] summarized the results of previous investigations [7,8,12]. They came to the conclusion that not all of the combined cystine reacts in the same way with sodium bisulfite, but that cystine can be divided into different fractions.…”

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The Reaction of Combined Cystine of Wool with Sodium Bisulfite

Schuringa

Schooneveldt

Konings

1951

Textile Research Journal

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THE DISULFIDE cross-linkages in wool,~ due to the combined cystine, are of fundamental importance concerning the physical and mechanical properties of the wool. The changes in the elastic properties of wool, brought about by different reagents, are mainly due to the breaking of these disulfide crosslinkages. ' If wool is treated with sodium bisulfite, according to Clarke [5] and Speakman [17], the combined cystine undergoes the following reaction: In 1946, Carter, Middlebrook, and Phillips [4] summarized the results of previous investigations [7,8,12]. They came to the conclusion that not all of the combined cystine reacts in the same way with sodium bisulfite, but that cystine can be divided into different fractions. According to these authors, about 25 % of the cystine does not react with sodium bisulfite, another 25% gives combined a-aminoacrylic acid, and one-half of the cystine is converted into cysteine and cysteine sulfonate side-chains. From the latter fraction part of the cystine can be restored by rinsing with water. Moreover, Speakman [18] found that when human hair is reduced with sodium bisulfite the cystine cross-linkages can be restored by rinsing with a solution containing no oxidizing agent.In connection with the extensive application of bisulfite for various treatments of wool, it is very important to know which reaction takes place in the wool and how this reaction can be influenced.Therefore, we investigated the final effect of the reaction between wool and sodium bisulfite, and the influence of rinsing. Experimental Procedure and ResultsSamples of 400 mg. of woolen yarn, degreased by extraction with a mixture of trichloroethylene and ethanol, were first soaked for 30 min. at room temperature in 125 times their weight of 5 % sodium bisulfite at pH 5.2,* and then reduced in an identical solution which had been preheated in a boiling water bath to 92°-95°C and kept at that temperature for 30 min. Heating the solution in a water bath prevented it from reaching the boiling point. Boiling had to be prevented because dispersion of tiny wool particles by the movement of the liquid might cause errors in the analytical data.The bisulfite-treated wool was then subjected to the following aftertreatments: (a) no rinsing, immediate hydrolysis; ( b ) before hydrolysis, rinsing for 20 hrs. in 0.50~o sodium acetate adjusted to pH 5.2 by the addition of acetic acid; (c) before hydrolysis, rinsing for 20 hrs. in 95% ethanol. Two additional wool samples were reduced for 60 min. and two more for 90 min. In each case, one sample was hydrolyzed without rinsing and one was hydrolyzed after 20 hrs. of rinsing with the sodium acetate buffer solution.The hydrolyses essential for determining cysteine and cystine were carried out in open test tubes with 10 ml. of 6N sulfuric acid. Hydrolyzing under C02 atmosphere did not make any difference.Although after 5 hrs. of boiling the keratin had not been completely hydrolyzed to amino acids, hydrolyzing for more than 5 hrs. caused no change in the values found for cysteine...

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The action of sulphites on the cystine disulphide linkages of wool

Abstract: When wool is immersed in solutions of NaHSO3 and then rinsed with water, some of the disulphide-S can be shown to have reacted as indicated in equation (1) [Elsworth & Phillips, 1938 a, b].

Cited by 45 publications

References 6 publications

The Elastic Properties of Chemically Modified Wools and Their Implications for Theories of Wool Structure

The Elastic Properties of Chemically Modified Wools and Their Implications for Theories of Wool Structure

Proteolysis of Wool and its S-Carboxymethyl Derivatives by Pronase and Other Proteases

The Reaction of Combined Cystine of Wool with Sodium Bisulfite

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