Abstract
The oligosaccharides maltose, maltotriose, mannotriose, and mannotetrose have been chemically attached to insulin molecules. Incubation of oligosaccharide and insulin at different molar ratios, with or without addition of cyanoborohydride, showed a nearly linear increase in carbohydrate attachment over time. The intravenous t( 1/2 ) of 125I-labeled sugar-insulin derivatives was identical to that of unmodified insulin (3.0 min). Biologic activity of these derivatives, assessed in rats by use of a blood glucose depression assay, did not differ significantly from control. These glycosylated insulin molecules are reversibly bound to the glucose-binding lectin Concanavalin A (Con A). Such sugar-insulin/lectin complexes serve as an insulin reservoir from which sugar-insulin molecules are displaced by glucose. Release of sugar-insulin molecules is a function of the particular sugar-insulin and of the ambient glucose concentration. Glucose displacement of glycosylated insulin complexed to Con A is in direct proportion to the amount of glucose present in the surrounding fluid. At each glucose concentration, the relative binding affinity of the maltotriose derivative is less than that of the mannotriose derivative, while the relative binding affinity of both maltotriose and mannotriose are less than that of the mannotetrose derivative. Prolonged incubation at 37°C causes sugar-insulin, like unmodified insulin, to spontaneously aggregate into high-mol-wt, nondiffusable complexes. This aggregation phenomenon was found to be markedly inhibited when glycosylated insulins were synthesized utilizing partially sulfated insulin. Results from the studies described in this report provide the biochemical basis for a closed-loop, glucose-controlled insulin delivery system, utilizing glycosylated insulin complexed to Con A.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 494-504 |
| Number of pages | 11 |
| Journal | Diabetes |
| Volume | 32 |
| Issue number | 6 I |
| State | Published - 1983 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Internal Medicine
Cite this
Glycosylated insulin complexed to concanavalin A. Biochemical basis for a closed-loop insulin delivery system. / Brownlee, M.; Cerami, A.
In: Diabetes, Vol. 32, No. 6 I, 1983, p. 494-504.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Glycosylated insulin complexed to concanavalin A. Biochemical basis for a closed-loop insulin delivery system
AU - Brownlee, M.
AU - Cerami, A.
PY - 1983
Y1 - 1983
N2 - The oligosaccharides maltose, maltotriose, mannotriose, and mannotetrose have been chemically attached to insulin molecules. Incubation of oligosaccharide and insulin at different molar ratios, with or without addition of cyanoborohydride, showed a nearly linear increase in carbohydrate attachment over time. The intravenous t( 1/2 ) of 125I-labeled sugar-insulin derivatives was identical to that of unmodified insulin (3.0 min). Biologic activity of these derivatives, assessed in rats by use of a blood glucose depression assay, did not differ significantly from control. These glycosylated insulin molecules are reversibly bound to the glucose-binding lectin Concanavalin A (Con A). Such sugar-insulin/lectin complexes serve as an insulin reservoir from which sugar-insulin molecules are displaced by glucose. Release of sugar-insulin molecules is a function of the particular sugar-insulin and of the ambient glucose concentration. Glucose displacement of glycosylated insulin complexed to Con A is in direct proportion to the amount of glucose present in the surrounding fluid. At each glucose concentration, the relative binding affinity of the maltotriose derivative is less than that of the mannotriose derivative, while the relative binding affinity of both maltotriose and mannotriose are less than that of the mannotetrose derivative. Prolonged incubation at 37°C causes sugar-insulin, like unmodified insulin, to spontaneously aggregate into high-mol-wt, nondiffusable complexes. This aggregation phenomenon was found to be markedly inhibited when glycosylated insulins were synthesized utilizing partially sulfated insulin. Results from the studies described in this report provide the biochemical basis for a closed-loop, glucose-controlled insulin delivery system, utilizing glycosylated insulin complexed to Con A.
AB - The oligosaccharides maltose, maltotriose, mannotriose, and mannotetrose have been chemically attached to insulin molecules. Incubation of oligosaccharide and insulin at different molar ratios, with or without addition of cyanoborohydride, showed a nearly linear increase in carbohydrate attachment over time. The intravenous t( 1/2 ) of 125I-labeled sugar-insulin derivatives was identical to that of unmodified insulin (3.0 min). Biologic activity of these derivatives, assessed in rats by use of a blood glucose depression assay, did not differ significantly from control. These glycosylated insulin molecules are reversibly bound to the glucose-binding lectin Concanavalin A (Con A). Such sugar-insulin/lectin complexes serve as an insulin reservoir from which sugar-insulin molecules are displaced by glucose. Release of sugar-insulin molecules is a function of the particular sugar-insulin and of the ambient glucose concentration. Glucose displacement of glycosylated insulin complexed to Con A is in direct proportion to the amount of glucose present in the surrounding fluid. At each glucose concentration, the relative binding affinity of the maltotriose derivative is less than that of the mannotriose derivative, while the relative binding affinity of both maltotriose and mannotriose are less than that of the mannotetrose derivative. Prolonged incubation at 37°C causes sugar-insulin, like unmodified insulin, to spontaneously aggregate into high-mol-wt, nondiffusable complexes. This aggregation phenomenon was found to be markedly inhibited when glycosylated insulins were synthesized utilizing partially sulfated insulin. Results from the studies described in this report provide the biochemical basis for a closed-loop, glucose-controlled insulin delivery system, utilizing glycosylated insulin complexed to Con A.
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UR - http://www.scopus.com/inward/citedby.url?scp=0020775864&partnerID=8YFLogxK
M3 - Article
C2 - 6354778
AN - SCOPUS:0020775864
VL - 32
SP - 494
EP - 504
JO - Diabetes
JF - Diabetes
SN - 0012-1797
IS - 6 I
ER -