chapter 10
Heteropolysaccharides I: Glycoproteins and Glycolipids
C h o lestero l (3-hydroxy-5,6-cholestene) b e lo n g s to a family of c o m p o u n d s derived from a fu sed , red u ced , n o n lin ear four-ring sy ste m of
cy clo p en taf a ]-p h e n a n th re n e. Bile a d d s , steroid h o rm o n es, a n d vitam in D m etabolites a re d eriv ed from cholesterol.
C onform ational
form ula
Glycosphingollplds (gangllosldes)
C eram id e o lig o sacch arid es consisting of a t le a st o n e resid u e of sialic a d d a re know n a s g an g lio sid es. T h e s e a re ab b rev iated by th e letter G
with a su b scrip t M (m ono), D (di), o r T (tri) to indicate th e n u m b er of sialyl re sid u es a n d a n u m b e r (or letter) to distinguish different m em b ers
of a g ro u p from e a c h other. G an g lio sid es a re particularly rich in n e rv o u s tissu e s. Following is th e stru ctu re of ganglioside G ut.
G alactosyl-p - ( 1 -3 ) N -acetylgalactosam inyl- p -( 1 - 4 ) g alacto sy l-p -( 1 - 4 ) glucosyl ceram id e
F I G U R E 1 0 -5
components of the bilayers and their role in natural
membranes. Liposomes are formed when phospholipids
are shaken vigorously in an aqueous medium. Electron
microscopic studies of liposome vesicle reveal “sealed”
concentric bilayers with the aqueous phase trapped on the
inside (Figure 10-8). Known substances can be entrapped
in liposomes, and permeability properties can be studied
under experimental conditions. Liposomes have potential
applications in medicine. Drugs and macromolecules (e.g.,
enzymes and nucleic acids) encapsulated in liposome sys-
tems can be targeted to a particular cell population or organ
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