Biology Reference
In-Depth Information
FIGURE 2.2
Nonpolar lipid analysis of LD from S. cerevisiae. For the thin layer chromatography (TLC)
analysis of nonpolar lipids different solvent systems were used (see
Section 2
). Cells were
grown to the stationary phase on glucose medium. Lipids were extracted and separated using
light petroleum/diethyl ether/acetic acid (35:15:1; per vol.) as the first, and light petroleum/
diethyl ether (49:1; v/v) as the second solvent system in the same direction (A). For the
TLC shown in (B), chloroform/acetone/acetic acid (45:4:0.5; per vol.) was used as a solvent
system. ST, standard mixtures.
from yeast LD show slightly lower Rf-values than cholesteryl oleate and triolein.
Additionally, small amounts of squalene on the top and free sterols on the bottom
of the TLC plate can be observed. Lipids in the TLC shown in
Fig. 2.2
B were sepa-
rated using chloroform/acetone/acetic acid (45:4:0.5; per vol.) as a solvent system
(see
Section 2
). 2.5
g protein equiv-
alent of LD sample from
S. cerevisiae
were loaded. As can be seen from
Fig. 2.2
B, LD
from
S. cerevisiae
contain very low amounts of DG and free sterols. However, these
two classes are well separated and can be identified by standards. Similar to TG and
SE, DG show a slightly lower Rf-value than pure diolein. SE and TG are not separated
in this TLC system and accumulate on the top of the TLC plate.
Phospholipids of LD are usually separated by two-dimensional TLC and analyzed
as described in
Section 2
.
Figure 2.3
shows a characteristic separation of individual
phospholipids from 15
g of ergosterol and diolein, respectively, and 1
m
m
g protein equivalent of yeast LD. Phosphatidylethanolamine,
phosphatidylcholine, and phosphatidylinositol are the most abundant phospholipids
from
S. cerevisiae
LD.
m
2.3.4
Lipid composition of LD from S. cerevisiae, P. pastoris, and
Y. lipolytica
As described above, TG and SE are major compounds of yeast LD. However, the
lipid composition of LD from different yeast genera can vary dramatically
