The chain weight of wool keratin

Middlebrook, W. R.

doi:10.1016/0006-3002(51)90068-6

Cited by 82 publications

(29 citation statements)

References 29 publications

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“…The same amino acids are also found as N-terminal and C-terminal residues of wool keratin (1)(2)(3)(4)(5)(6). The same seven N-terminal groups have also been found recently in feather keratin (10).…”

Section: Resultssupporting

confidence: 68%

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The N- And C-Terminal End Groups of Hair Keratin

Kerr¹,

Godin²

1959

Can. J. Chem.

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The N-terminal and the C-terminal residues of human and horse hair and partially reduced hair have been determined. Aspartic acid, glutarnic acid, glycine, serine, threonine, alanine, and valine were identified as N-terminal groups. Aspartic acid, glutarnic acid, glycine, serine, threonine, and alanine were identified as C-terminal groups. These are the same N-terminaland C-terminal amino acids as have been found previously for wool and feather keratin. INTRODUCTIONThe purpose of the following work was t o establish a procedure which would serve t o differentiate among the hair keratins of different species of animals, including man. A t present a visual microscopic procedure is used in practically all forensic work involving hair. For most cases this is sufficient, particularly if negative results will suffice. In some cases, however, the microscope is simply inadequate in providing the information required by the examiner.Recently, the N-terminal and the C-terminal residues of wool keratin were determined (1, 2, 3 , 4 , 5, 6). Complex mixtures of end groups were found and it was hoped that some qualitative differences could be established between the hair keratins of different species using these methods. This paper reports the identification of N-terminal and C-terminal residues in human and horse hair. EXPERIMENTALHair.-The human hair was obtained from the "N" Division, R.C.M.P. Barracks, and was exclusively male. The horse hair was obtained from the "N" Division, R.C.M.P. Stables, and was exclusively tail hair. T o degrease the hair it was extracted in a Soxhlet for 2 hours each with acetone and ether and then air-dried. Finely ground hair was obtained by grinding the hair in liquid nitrogen in a porcelain mortar.Dinitropheny1ation.-Finely ground hair (0.5 g) was suspended in water (12 ml) containing sodium bicarbonate (0.5 g). Ethanol (25 ml) containing 1-fluoro-2,4-dinitrobenzene (FDNB) (0.86 g) was added and the mixture was shaken for 48 hours a t 40' C (2). The hair was then isolated by filtration, washed with water, alcohol, and ether. When partly reduced keratin was dinitrophenylated, the mixture was first extracted with ether, then acidified. T h e insoluble dinitrophenyl-proteins (DNP-proteins) were centrifuged down and washed with water, alcohol, and ether.Hydrazino1ysis.-The method described by Niu and Fraenkel-Conrat (7) was used.Hydrolysis.-The DNP-proteins were hydrolyzed in 6 N HCl in sealed tubes for 24 hours a t 100' C.Chromatography.-The DNP-amino acids were spotted on Whatman paper No. 3 MM buffered a t pH 6. T h e chromatograms were developed with tert-amyl alcohol saturated with pH 6 phthalate buffer (8). Each spot obtained was run again after elution from t h e paper. The same paper was used for the second run but the phthalate buffer alone was used as solvent. In the buffer alone the R, values are different from those obtained in tert-amyl alcohol.Reduction.-Hair keratin was partly reduced with sodium thioglycolate (9). Hair (0.5 g) was suspended in water (25 ml) containing sod...

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Section: Resultssupporting

confidence: 68%

“…Ethanol (25 ml) containing 1-fluoro-2,4-dinitrobenzene (FDNB) (0.86 g) was added and the mixture was shaken for 48 hours a t 40' C (2). The hair was then isolated by filtration, washed with water, alcohol, and ether.…”

Section: Methodsmentioning

confidence: 99%

The N- And C-Terminal End Groups of Hair Keratin

Kerr¹,

Godin²

1959

Can. J. Chem.

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“…Dinitrophenylation was carried out by treating the wool fibers for several days with an ethanolic solution of dinitrofluorobenzene. 13 Grafting procedure Graftcopolymerization was carried out as follows.…”

Section: Chemical Modification Of Woolmentioning

confidence: 99%

Manganese(IV)-Initiated Graftcopolymerization of Methyl Methacrylate on Wool Fibers

Kantouch

Abdel-Fattah

Hebeish

1972

Polym J

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ABSTRACT:Potassium permanganate-induced graftcopolymerization of methyl methacrylate(MMA) on wool fibers was investigated under a variety of conditions. The graft yield was favourably influenced by increasing the reaction time and monomer and initiator concentration. Raising the reaction temperature from 50 to 70°C causes a significant increment in the graft yield. Using 4-mmolar potassium permanganate and 6-% methyl methacrylate at pH 1 (pH was adjusted by nitric acid), a graft yield of 70% could be obtained at 70°C in two hours reaction time. This yield could be increased up to 180% if wool is treated with thioglycolic acid prior to grafting. Dinitrophenylated wool, on the other hand, showed a negligible graft yield, indicating that amino and hydroxyl groups in the wool molecules acts as sites for grafting. The consumption of permanganate was so rapid that about 60% of it was consumed in the first thirty minutes of the reaction during oxidation. On the other hand, relatively shorter time was required to cause full consumption during grafting. The excess of permanganate during grafting over that during oxidation was anticipated to initiation and termination of homopoly (methyl methacrylate). Wool with a graft yield of ca. 50% is nearly insoluble in alkali compared to the untreated one which is nearly completely soluble under similar conditions. A tentative mechanism for grafting on wool induced by permanganate was proposed.

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“…Harris and Hindley 1961). We do not think that ·the acetyl groups found here are located predominantly on the lysine residues since the €-amino groups of wool (Middlebrook 1951) and extracted wool proteins are available to 1,2,4-fluorodinitrobenzene under mild conditions, e.g. in the lowsulphur proteins at least 90% of the dysyl residues react.…”

Section: (C) N-acetyl Oontent Of Wool and Wool Proteinsmentioning

confidence: 77%

N-Acetyl Groups in Wool and Extracted Wool Proteins

O'donnell¹,

Thompson²,

Inglis³

1962

Aust. Jnl. Of Bio. Sci.

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SummaryN . acetyl groups have been shown to exist in wool and in proteins extracted from wool after reduction with mercaptoethanol followed by alkylation with iodoacetate or after oxidation with performic acid. The evidence suggests that these acetyl groups are located on N-terminal amino groups of peptide chains rather than on the E-amino groups of lysine.Acid hydrolysis with 12N sulphuric acid was found to be preferable to alkaline hydrolysis for the release of acetic acid from the N-acetyl groups, since alkaline hydrolysis produced volatile acids other than acetic acid.

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The chain weight of wool keratin

Cited by 82 publications

References 29 publications

The N- And C-Terminal End Groups of Hair Keratin

The N- And C-Terminal End Groups of Hair Keratin

Manganese(IV)-Initiated Graftcopolymerization of Methyl Methacrylate on Wool Fibers

N-Acetyl Groups in Wool and Extracted Wool Proteins

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