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Provedor de dados: 189
País: France
Título: Structure and orientation of pancreatic colipase in a lipid environment: PM-IRRAS and
Brewster Angle Microscopy studies
Autores: Allouche, M.; Castano, S.; Colin, D.; Desbat, B.; Kerfelec, B.
Data: 2007
Ano: 2007
Palavras-chave: ACTIVITE ENZYMATIQUE; PANCREAS; SPECTROSCOPIE PM-IRRAS;
COLIPASE.
Resumo: Colipase is a key element in lipase-catalyzed dietary lipids hydrolysis. Although devoid
of enzymatic activity, colipase promotes pancreatic lipase activity in the physiological
intestinal conditions by anchoring the enzyme on the surface of lipid droplets.
Polarization modulation infrared reflection absorption spectroscopy combined with
Brewster angle microscopy studies was performed on colipase alone and in various lipid
environments to obtain a global view of both conformation and orientation and to assess
lipid perturbations. We clearly show that colipase fully inserts into a dilaurin monolayer
and promotes the formation of lipid/protein domains, whereas in a phospholipid
environment its insertion is only partial, limited to the polar head group. In a mixed 70%
phosphatidylcholine/30% dilaurin environment, colipase adsorbs to but does not penetrate
deeply into the film. It triggers the formation of diglyceride domains under which it
would form a rather uniform layer. We also clearly demonstrate that colipase adopts a
preferred orientation when dilaurin is present at the interface. In contrast, at a neutral
phospholipid interface, the infrared spectra suggest an isotropic orientation of colipase
which could explain its incapacity to reverse the inhibitory effects of these lipids on the
lipase activity
Tipo: Journal Article
Idioma: Inglês
Identificador: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD20085218fbca&uri=/notices
/prodinra1/2008/01/
Fonte: Biochemistry. 2007, 46 (51) : 15188-15197