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Horm Metab Res 1983; 15(6): 263-268
DOI: 10.1055/s-2007-1018691
© Georg Thieme Verlag, Stuttgart · New York

Hyperglycemia Alters the Physico-Chemical Properties of Proteins in Erythrocyte Membranes of Diabetic Patients

P. Compagnucci, Maria Giulia Cartechini, G. Bolli1 , R. S. Cataliotti2 , Lucia Pellei2 , C. Cirotto3 , P. De Feo1 , F. Santeusanio, P. Brunetti1
  • Institute of Clinical Medicine, University of Perugia, Perugia, Italy
  • 1Institute of Medical Pathology, University of Perugia, Perugia, Italy
  • 2Institute of Physical Chemistry, University of Perugia, Perugia, Italy
  • 3Institute of Histology and Embryology, University of Perugia, Perugia, Italy
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Publication History

1982

1982

Publication Date:
14 March 2008 (online)

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Summary

We measured the absorption spectra of erythrocyte ghosts in the interval of 180-250 nm wavelength and calculated an index order/disorder (Io/d) by the ratio of the absorbances determined at 225 and at 195 nm, i.e. the higher this ratio, the better the structure order of the erythrocyte membrane proteins examined. The Io/d was significantly lower in nonregulated diabetics (n=24) than in normals (n=14) (12.14±0.32 versus 14.98±0.20, 2p< 0.001). In diabetics the Io/d correlated inversely with the mean daily plasma glucose (r= -0.51, 2p< 0.02). The correlation was better with percent stable HbAI (r= -0.62, 2p< 0.005). In 4 initially non regulated diabetics the Io/d was measured 4-5 times over a two month period while on an appropriate insulin regimen which resulted in a fair glycemic control. The Io/d and percent stable HbAI slowly and parallely changed towards normal values.

The Io/d was measured also 0, 12, 36, 60, and 108 hours after incubation in vitro of erythrocyte ghosts at 0, 20, and 37°C at different glucose concentrations (0, 25, and 100 mmol/l). A decrease in the Io/d was observed, which was more pronounced at the latest times, at 37°C, and at the highest glucose concentrations. Finally, the incubation of erythrocyte ghosts with labeled D-(14C)-glucose resulted in a linkage with all membrane proteins, as assessed by the radioactivity found in all the bands obtained after SDS gel electrophoresis.

Our data suggest that erythrocyte ghosts exposed to an abnormally high glucose concentration, as in non regulated diabetics, undergo alterations of physico-chemical properties of membrane proteins.

These alterations can be precisely measured and seem to be a direct consequence not only of a slow process of glycosylation of membrane proteins, but also of a short-term interacion between glucose and proteins. The demonstration of such a “glucotoxicity” could be important to explain the abnormalities reported in the red cells of diabetics.

Key-Words:

Erythrocyte Membranes - Glycosylation - Diabetes - UV Spectra

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