The isoelectric point of wool

Harris, Meyer M.

doi:10.6028/jres.008.058

Cited by 13 publications

(10 citation statements)

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“…The total nitrogen contents of the preparations appear to bear no direct relation to their isoelectric points. This same result with wool was noted by Harris [12] in 1932, who found that a difference of 1 percent in nitrogen content did not result. in different isoelect,ric points.…”

Section: Amide Nitrogen Content Andsupporting

confidence: 84%

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Studies on the purification of collagen

Cassel¹,

Kanagy²

1949

J. RES. NATL. BUR. STAN.

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Several methods of purifying collagen were studied . The effects of particular treatments on collagen were followed by nitrogen determina tions, by electrometric t itra tion analyses, and by electrophor etic measurements.Treatment of the raw material with t rypsin , as in the conventional method for t he preparation of collagen, results in changes t hat lead to a degradation of the collagen in s ubsequent extr actions. Treatment with dilu te salt solut ion followed by trypsin produces a rpaterial of compal'ati vely low isoelectic point (pH 5.5). Apparently soakin g in dilute salt solu t ion is not detrimental to collagen, and it is r ecommended that this type of extraction be sub tituted for t he extraction with trypsin.A technique for removing all but a negligible part of the mineral content from collagen is described, and a pr ocedure is recommended for use in the preparation of ash-free gelatin .A specification is proposed for purified collagen: (1) The water extract shall have a pH range of 6.0 to 7.0 ; (2) the isoelectric point (determined electrophoretioally) shall be between pH 6.0 and 7.5; (3) the material shall have an ash content of less than 0.1 percent, total nitrogen content of 17.8 to 18.1 percent, and au amide nitrogen content (determined by hydrolyzing for 20 hours in 0.1 N hydrochloric acid at 90° C) of at least 3.8 perccnt, expre1'sed as perce ntage of total nitrogen.

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Section: Amide Nitrogen Content Andsupporting

confidence: 84%

“…A practical application of the cell in the investigation of wool protein is given by Harris [12]. The microscope was used with an 8-mm objective and a 20 X eyepiece.…”

Section: Electrophoretic Analysismentioning

confidence: 99%

Studies on the purification of collagen

Cassel¹,

Kanagy²

1949

J. RES. NATL. BUR. STAN.

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“…It will be necessary to include in the development of a complete theory of the effect of pH on the electric mobilities of crystalline amino acids, the effect of adsorbed hydrogen ions in addition to the entrance of dissolved amino acid molecules into the surface, even though the effects of hydrogen ions may be less important than isomorphous ions. In the case of the surfaces of the keratins, such as wool (25), hair, skin, and finger nails (26), the electrokinetic properties are probably influenced more than adsorbed proteins by the constraints occurring at the surface of the crystal lattice. Since in the case of the keratins the elongated protein molecules are arranged side by side and held together by S--S linkages for the most part (27,28), it seems likely that the constraints imposed on the reacting groups of the sur-ELECTROKINETIC PHENOMENA.…”

Section: Discussionmentioning

confidence: 99%

Electrokinetic Phenomena

Abramson

Moyer

1938

Journal of General Physiology

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1. Although the isoelectric points of dissolved cystine, tyrosine, and aspartic acid molecules lie at widely differing pH values, the isoelectric points of the surfaces of these substances in the crystalline state are all near pH 2.3. This was found to be true in solutions of hydrochloric acid and in acetate buffers of approximately constant ionic strength. 2. When suspended in gelatin, tyrosine and cystine crystals adsorb the protein and attain a surface identical in behavior with gelatin-coated quartz or collodion particles. 3. Aluminum ions at low concentrations reduce the electric mobilities of tyrosine crystals to zero in a manner analogous to their effect on other surfaces. 4. Alkyl benzene droplets also have their electric mobility reduced to zero at low pH values but, unlike the amino acids, a change in sign was never noticed. 5. The mobility of tyrosine crystals is independent of crystal length between 2–100µ. Below this size the mobilities are decreased. 6. These results are discussed in connection with the concept of the general definition of the isoelectric point and the behavior of certain insoluble proteins such as wool and silk fibroin.

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“…This indicates that the negative effect for leaching of PFAS species in the presence of multivalent cations in landfill leachate could be due to the cations acting as bridges between negatively charged PFASs and negatively charged carpet surfaces (i.e., [carpet surface] − + Ca 2+ + R-COO − or R-SO 3 − ). This mechanism results from the pK a of PFASs (PFCAs (<0.52) and PFSAs (< −3.26)) and the net carpet charge of zero for pH 3.4 according to Harris,42 which is less than the leachate pHs studied.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Compositional Effects on Leaching of Stain-Guarded (Perfluoroalkyl and Polyfluoroalkyl Substance-Treated) Carpet in Landfill Leachate

Kim

Grace

et al. 2015

Environ. Sci. Technol.

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Perfluoroalkyl and polyfluoroalkyl substances (PFASs) from stain-guard treated carpets in landfills continue to be released into the environment. To understand the leaching of PFASs from carpets to landfill leachate as a function of environmental factors, leaching concentrations of ten perfluoroalkyl carboxylic acids and four perfluoroalkyl sulfonic acids were quantified for different pHs, contact times, mixing speeds, and temperatures. Partitioning from carpet to leachate and distilled water at different pHs showed negligible differences. The total concentration of leaching PFASs in distilled water was approximately 1 ng L(-1) higher than in landfill leachate, indicating that the presence of multivalent cations in leachate could have a negative effect on leaching of PFASs. For all PFASs monitored, leaching increased with increasing contact time and temperature. Perfluorohexanoic and perfluoroheptanoic acids experienced the largest increases with contact time and temperature. Gibbs free energy (ΔG > 0), enthalpy (ΔH > 0), and entropy energy (ΔS < 0) indicated that PFAS leaching from carpet was dominantly controlled by entropy-driven processes and did not differ significantly among individual PFASs. PFAS concentrations in leachate with rotation of an end-over-end contactor were higher than under static conditions, but otherwise, varying the rotation speed had negligible influence. The results provide useful information for management of discarded stain-guard carpets in landfills.

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The isoelectric point of wool

Cited by 13 publications

References 0 publications

Studies on the purification of collagen

Studies on the purification of collagen

Electrokinetic Phenomena

Compositional Effects on Leaching of Stain-Guarded (Perfluoroalkyl and Polyfluoroalkyl Substance-Treated) Carpet in Landfill Leachate

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