Full resolution (JPEG) - On this page / på denna sida - IV. Animal Fats and Phosphatides - 2. Phospatides
<< 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.
244 ANIMAL FATS AND PHOSPHATIDES.
The same also applies to the claims as to the quantity of lecithin
in various organs and tissues as well as in different ages. In these cases
the lecithin has not been prepared in a pure state, and the determina-
tions represent only the approximate quantity of phosphatides. These
determinations of Siwertzow, Glikin and Nerking,1
show that lecithins
(phosphatides) occur abundantly in the bone marrow, suprarenal capsule,
heart and lungs, besides in the spinal marrow, brain, and egg, and also
that the quantity varies strikingly in different varieties of animals.
Nerking found 41.7 per cent lecithin in the bone marrow and 21.33
per cent in the suprarenal capsule of the sea-urchin when calculated on
the living organs, while the corresponding results in the rabbit were 2.71
and 2.39 per cent, respectively.
The statements as to the properties of the lecithins apply chiefly to
the lecithin of the hen’s egg, which since Hoppe-Seyler and Diaconow’s
time has been considered as distearyl-lecithin without any positive founda-
tion. Other lecithin preparations correspond essentially with this, and
certain differences between the various lecithins may be possibly due
to decomposition products or to admixture with other phosphatides.
It is still questioned whether the so-called distearyl-lecithin is a unit
body or not.
Lecithin may be obtained in grains or warty masses composed of small
crystalline plates by thoroughly cooling its solution in strong alcohol. In
the dry state it has a waxy appearance, is plastic, but forms pulverizable
masses when dried in vacuum, and is soluble in alcohol, especially on
heating (to 40-50° C.) ; it is less soluble in ether. It is dissolved also by
chloroform, carbon disulphide, benzene, and fatty oils. The solution
of lecithin from egg-yolk is dextrorotatory (Ulpiani 2
). P. Mayer 3
claims to have prepared racemic lecithin from ordinary lecithin, and
Z-lecithin from the r-lecithin by cleavage with lipase. As he did not
make use of pure lecithin it is difficult to judge his results. The solu-
tion of lecithin in alcohol-ether or chloroform is precipitated by acetone,
although not completely. It swells in water to a pasty mass which shows
under the microscope slimy, oily drops and threads, so-called myelin
forms (see Chapter XI). On warming this swollen mass or the concen-
trated alcoholic solution, decomposition takes place with the produc-
tion of a brown color. On allowing the solution or the swollen mass to
stand, decomposition takes place and the reaction becomes acid. Accord-
ing to the investigations of Long 4
the lecithins seem to be much more
1
Siwertzow, see Biochem. Zeitschr., 2, p. 310; Glikin, Biochem. Zeitschr., 4 and
7; Nerking, ibid., 10.
2
Chem. Centralbl., 1901, 2, 30 and 193.
3
Biochem. Zeitschr., 1.
4
Journ. of Arner. chem. Soc, 30, 1908.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
