The influence of degree-of-branching and molecular mass on the interaction between dextran and Concanavalin A in hydrogel preparations intended for insulin release

Ian Benzeval, Adrian Bowyer, John Hubble

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)
227 Downloads (Pure)

Abstract

The interactions of a number of commercially available dextran preparations with the lectin Concanavalin A (ConA) have been investigated. Dextrans over the molecular mass range 6 x 10(3)-2 x 10(6) g mol(-1) were initially characterised in terms of their branching and hence terminal ligand density, using NMR. This showed a range of branching ratios between 3% and 5%, but no clear correlation with molecular mass. The bio-specific interaction of these materials with ConA was investigated using microcalorimetry. The data obtained were interpreted using a number of possible binding models reflecting the known structure of both dextran and the lectin. The results of this analysis suggest that the interaction is most appropriately described in terms of a two-site model. This offers the best compromise for the observed relationship between data and model predictions and the number of parameters used based on the chi-squared values obtained from a nonlinear least-squares fitting procedure. A two-site model is also supported by analysis of the respective sizes of the dextrans and the ConA tetramer. Using this model, the relationship between association constants, binding energy and molecular mass was determined.
Original languageEnglish
Pages (from-to)143-148
Number of pages6
JournalEuropean Journal of Pharmaceutics and Biopharmaceutics
Volume80
Issue number1
DOIs
Publication statusPublished - Jan 2012

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