Biology Reference
In-Depth Information
employed homocysteine linked to the membrane through a palmitic acid. Homocysteine
exists in a cyclic structure that disrupts the liposomal membrane under acidic conditions
but does not affect membrane permeability near neutral pH (
Figure 15.6
, Panel (a)). These
liposomes were only useful between pH 7.4 and pH 6.0. It was predicted that these liposomes
(a)
NH
2
.HCl
NH
2
OH
HS
O
S
O
pH 5.0
pH 7.4
HOMOCYSTEINE
(b)
O
O
N
O
O
P
O
H
O
O
H
O
O
O
H
H
H
FIGURE 15.6
Panel (a)
. Structure of homocysteine at pH 5.0 and pH 7.4. Reprinted with permission
[59]
. The low
pH cyclic conformation disrupts the liposome membrane, increasing leakiness. The neutral pH conformation does
not affect liposome membrane permeability
[60]
.
Panel (b)
. N-succinyl 1,2-dioleoyl-3-phosphoglycerol. Reprinted
with permission
[61]
.
