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Download fileDendrimer-Linked Antifreeze Proteins Have Superior Activity and Thermal Recovery
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posted on 2015-09-16, 00:00 authored by Corey
A. Stevens, Ran Drori, Shiran Zalis, Ido Braslavsky, Peter L. DaviesBy
binding to ice, antifreeze proteins (AFPs) depress the freezing
point of a solution and inhibit ice recrystallization if freezing
does occur. Previous work showed that the activity of an AFP was incrementally
increased by fusing it to another protein. Even larger increases in
activity were achieved by doubling the number of ice-binding sites
by dimerization. Here, we have combined the two strategies by linking
multiple outward-facing AFPs to a dendrimer to significantly increase
both the size of the molecule and the number of ice-binding sites.
Using a heterobifunctional cross-linker, we attached between 6 and
11 type III AFPs to a second-generation polyamidoamine (G2-PAMAM)
dendrimer with 16 reactive termini. This heterogeneous sample of dendrimer-linked
type III constructs showed a greater than 4-fold increase in freezing
point depression over that of monomeric type III AFP. This multimerized
AFP was particularly effective at ice recrystallization inhibition
activity, likely because it can simultaneously bind multiple ice surfaces.
Additionally, attachment to the dendrimer has afforded the AFP superior
recovery from heat denaturation. Linking AFPs together via polymers
can generate novel reagents for controlling ice growth and recrystallization.