Full resolution (JPEG) - On this page / på denna sida - II. The Protein Substances - I. Simple Proteins - B. Albuminoids or Albumoids
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KERATINS. 113
It seems that there exist a number of keratins, and these form a special
group of bodies. This fact, together with the difficulty in isolating the
keratin from the tissues in a pure condition without a partial decom-
position, is sufficient explanation for the variation in the elementary
composition given below. As examples the analyses of a few tissues
rich in keratin and of keratins are given:1
c h n s o
Human hair 43.72 6.34 15 06 4.95 29.93 (Rutherford
and Hawk)
Nail 51.00 6.94 17.51 2.80 21.75 (Mulder)
Neurokeratin.. . . 56.11-58.45 7.26-8.02 11.46-14.32 1.63-2.24 (Kuhne)
Neurokeratin 56.61 7.45 14.17 2.27 (Argiris)
Horn (average) . . 50.86 6.94 3.20 (Horbaczewski
Tortoise shell 54.89 6.56 16.77 2.22 19.56 (Mulder)
Shell membrane. . 49.78 6.64 16.43 4.25 22.50 (Lindvall)
Egg membrane . . 53.92 7.33 15.08 1.44 (Pregl)
(ScyIlium)
Mohr 2
has determined the quantity of sulphur in various keratin
substances. Sulphur is in great part in loose combination, and it is
removed principally by the action of alkalies (as sulphides), or indeed in
part by boiling with water. Combs of lead after long usage become black,
and this is due to the action of the sulphur of the hair. On heating keratin
with water in sealed tubes to a temperature of 150° C. or higher, it dis-
solves with the elimination of sulphureted hydrogen or mercaptan
(Batjer), and the solution contains proteose-like substances (Kruken-
berg) called atmidkeratin and atmidkeratose by Bauer.3 Keratin is
dissolved by alkalies, especially on warming, producing besides alkali
sulphides also proteose substances.
Besides the well-known cleavage products such as leucine, tyrosine,
aspartie acid, glutamic acid, arginine, and lysine, Fischer and Dorping-
haus 4
have found glycocoll, alanine, valine, proline, serine, phenyla-
lanine, and pyrrolidone-carboxylic acid (secondary from glutamic acid)
among the cleavage products of horn substances. Emmerling claims
to have found cystine as a sulphurized cleavage product, but K. Morner
1 Rutherford and Hawk, Journ. of biol. Chem., 3; Mulder, Versuch einer allgem.
physiol. Chem., Braunschweig, 1844-51; Kiihne, Zeitschr. f. Biologie, 26; Horbaczew-
ski, see Drechsel in Ladenburg’s Handworterbuch. d. Chem., 3; Lindvall, Mary’s
Jahresbericht, 1881; Argiris, Zeitschr. f. physiol. Chem., 54; Pregl., ibid., 56.
2
Zeitschr. f. physiol. Chem., 20.
3
Krukenberg, Untersuch. iiber d. chem. Bau d. Eiweisskorper, Sitzungsber. d.
Janaischen Gesellsch. f. Med. u. Naturwissensch., 1886; Bauer, Zeitschr. f. physiol.
Chem., 35.
4
Zeitschr. f. physiol. Chem., 36, which contains also the older literature.
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