Glucose-Binding Property of Pegylated Concanavalin a |
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Authors: | Kim Jung Ju Park Kinam |
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Institution: | (1) Departments of Pharmaceutics and Biomedical Engineering, Purdue University, West Lafayette, Indiana, 47907 |
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Abstract: | Purpose. Concanavalin A (Con A) has been used in the development of sol-gel phase-reversible hydrogels for modulated insulin delivery. The usefulness of Con A has suffered from its poor aqueous solubility and stability. The goal of this study was to modify Con A with poly(ethylene glycol) (PEG) and examine the water solubility and stability of the PEGylated Con A.
Methods. Con A was PEGylated using monomethoxy poly(ethylene glycol) p-nitrophenol carbonates, and the extent of PEGylation was determined by the fluorescamine method. The stability of the PEGylated Con A was examined by measuring the time-dependent absorbance at 630 nm. The binding affinities of glucose and allyl glucose to native- and PEGylated-Con A were measured by the equilibrium dialysis method.
Results. The total number of PEG molecules that can be grafted to Con A was 10. As the number of grafted PEG chains per each Con A was increased up to 5, the binding affinity of glucose was gradually increased and reached the maximum. The solubility and stability of PEGylated Con A were improved significantly over those of native Con A. The binding affinity of allyl glucose to Con A was not changed much by PEGylation. When the extent of PEGylation was excessive (i.e., the number of grafted PEG chains per each Con A was larger than 5), however, the binding affinities of both glucose and allyl glucose were decreased significantly.
Conclusions. PEGylation of Con A resulted in improved aqueous solubility and stability of Con A. The binding affinity of glucose increased and reached the maximum when the extent of PEGylation was 50%. Advantages of PEGylated Con A over native Con A are improved aqueous solubility, enhanced long-term stability, and higher glucose sensitivity. |
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Keywords: | concanavalin A PEGylation glucose binding affinity allyl glucose solubility stability |
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