Synthesis and aggregative properties of GM1 ganglioside (IV3Neu5AcGgOse4Cer) containing D-(+)-2-hydroxystearic acid.
GM1 ganglioside containing a hydroxylated fatty acid moiety, GM1(OH), was synthesized starting from lyso-GM1 and D-(+)-2-hydroxystearic acid. The aggregative, geometrical and distribution properties of GM1(OH) were compared with those of stearic acid containing GM1 ganglioside; laser light scattering measurements, differential scanning calorimetry and fluorescence spectroscopy were used. GM1 and GM1(OH) are present in solution as micelles with a hydrodynamic radius of 58.7 and 60.0 A, and molecular mass of 470 and 570 kDa, respectively. The surface area occupied by the monomer of GM1(OH) at the lipid-water interface of the aggregate was calculated to be 117 A2, which is 3 A2 lower than that determined for GM1. Proton NMR analyses of GM1 and GM1(OH) suggest different three-dimensional structures at the ganglioside lipid-water interface. Both GM1(OH) and GM1 inserted into dipalmitoylphosphatidylcholine (DPPC) vesicles undergo segregation phenomena, with the formation of ganglioside-enriched microdomains, but GM1(OH) shows a higher degree of dispersion in the DPPC matrix and exerts a lower rigidifying effect than does GM1.
Sonnino
S
S
Department of Medical Chemistry and Biochemistry, University of Milan Medical School, Italy.
Acquotti
D
D
Cantu
L
L
Chigorno
V
V
Valsecchi
M
M
Casellato
R
R
Masserini
M
M
Corti
M
M
Allevi
P
P
Tettamanti
G
G
D015060:1,2-Dipalmitoylphosphatidylcholine; D002152:Calorimetry, Differential Scanning; D002240:Carbohydrate Sequence; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005677:G(M1) Ganglioside / Q000138:chemical synthesis* / Q000737:chemistry*; D007834:Lasers; D008051:Lipid Bilayers / Q000737:chemistry; D008823:Micelles; D008969:Molecular Sequence Data; D015394:Molecular Structure; D008970:Molecular Weight; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013229:Stearic Acids / Q000737:chemistry*
D008051:Lipid Bilayers; D008823:Micelles; D013229:Stearic Acids; D015060:1,2-Dipalmitoylphosphatidylcholine; D005677:G(M1) Ganglioside; C061806:2-hydroxystearic acid