Full resolution (JPEG) - On this page / på denna sida - II. The Protein Substances - I. Simple Proteins - A. True Albuminous Bodies - Synopsis of the Most Important Properties of the Different Groups of Albuminous Bodies
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
10S THE PROTEIN SUBSTANCES.
which are not soluble in water, dilute salt solutions, or very dilute alkalies,
and only dissolve after being modified by strong alkalies.
Histones are basic proteins which stand to a certain extent between
the strongly basic protamines (see below) and the true proteins. Their
content of nitrogen varies between 16.5 and 19.8 per cent, and in certain
instances is not higher than in other proteins, especially vegetable pro-
teins. According to Kossel and Kutscher and Lawrow they are,
on the contrary, richer in basic nitrogen, and especially yield more arginine
than other proteins. Kossel first isolated a peculiar protein substance
from the red corpuscles of goose blood which was precipitated by ammonia,
and because of its similarity in certain regards to the peptones (in the
old sense) he called it histone. At the present time a number of very
different bodies are described as histones, such as those obtained from
nucleohistone (Lilienfeld), from haemoglobin (globin according to
Schulz), from mackerel spermatozoa (scombron according to Bang),
from the codfish (gadushistone according to Kossel and Kutscher),
from the burbot (lotahistone, Ehrstrom), and from the sea-urchin
(arbacin, Mathews), although probably not all are true histones,
especially the above mentioned globin. 1
Sulphur has been found in those histones in which it has been tested
for, but they do not, at least not all, give the lead-blackening test with
alkali and lead acetate. They give the biuret test, but as a rule only
a faint Millon’s reaction. The goose-blood histone first studied by
Kossel gives the three following reactions: First, the neutral salt-
free solution does not coagulate on boiling; second, gives a precipitate
with ammonia which is insoluble in an excess of the precipitant; third,
gives a precipitate with nitric acid which disappears on heating and
reappears on cooling.
The different histones behave differently with these three reactions,
and hence they are not specific. On the other hand, all histones seem
to be precipitated from neutral solution by alkaloid reagents, and they
also produce precipitates in protein solutions. These two reactions are
likewise not specific for the histones, as the protamines have a similar
behavior. The histones differ from the protamines by having a much
lower content of basic nitrogen, and also probably by always containing
sulphur. True proteins, as Osborne’s2
edestan, also give these two
reactions; therefore it is impossible by qualitative tests alone to identify
1
Kossel Zeitschr. f. physiol. Chem., 8, and Sitzungbers. der Gesellsch. zur Beford.
d. ges Naturwiss. zu Marburg, 1897; Kossel and Kutscher, ibid., 1900, and Zeitschr.
f physiol. Chem., 31; Lawrow, ibid., 28, and Ber. d. d. chem. Gesellsch., 34; Lilienfeld,
Zeitschr. f. physiol. Chem., 18; Schulz, ibid., 24; Bang, ibid., 27; Ehrstrom, ibid.,,.
32; Mathews, ibid, 23.
2 Zeitschr. f. physiol. Chem., 33.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
