Relationship between isoelectric point of native and chemically modified insulin and liposomal fusion.
Native insulin causes fusion of negatively charged liposomes in the pH range from 3.0 to 5.5. In marked contrast, insulin with all three amino groups succinylated did not show fusion ability at any pH. On the other hand, insulin amidated with glycine methyl ester with all six carboxyl groups blocked shifted its activity to higher pH, showing a pH range of activity from 3.0 to 7.4. When the carboxyl groups were recovered by hydrolysis of methoxyl groups from glycine methyl ester-treated insulin, the protein obtained (glycyl-insulin with six free carboxyl groups) behaved as native insulin. A good correlation between the isoelectric point values of insulin and its derivatives and their fusion properties was found.
Farías
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Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas (INSIBIO) (CONICET-UNT), San Miguel de Tucumán, Argentina.
López Viñals
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Posse
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Morero
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D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007328:Insulin / Q000031:analogs & derivatives / Q000502:physiology*; D007526:Isoelectric Point; D008561:Membrane Fusion; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D013329:Structure-Activity Relationship
D007328:Insulin; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines