"Domain" Coil-globule Transition in Homopolymers
Digital Object Identifier (DOI)
The temperature-induced coil-globule transition has been studied in dilute aqueous solutions (with 200 mg/L SDS) for different fractions of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-isopropylmethacrylamide) (PNIPMAM) using scanning microcalorimetry, diffusion, and size-exclusion chromatography (FPLC). It has been shown that both these polymers undergo a coil-globule transition upon temperature increase. This transition is accompanied by cooperative heat absorption and a decrease of heat capacity, which makes it similar to the cold denaturation of globular proteins.
The globule-coil transition is an "all-or-none" process only for the fraction with the lowest molecular weight (~10x10^3), while fractions of larger molecular weights behave as if they consist of quasi-independent cooperative units, the "domains". The number of "domains" in a macromolecule is proportional to the molecular weight of the polymer. This suggests that the "domain" character of cooperative transitions in large proteins does not, in principle, need evolutionary-selected amino acid sequences but can occur even in homopolymers.
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Citation / Publisher Attribution
Macromolecules, v. 28, issue 22, p. 7519-7524
Scholar Commons Citation
Tiktopulo, Elisaveta I.; Uversky, Vladimir N.; Lushchik, Vanda B.; Klenin, Stanislav I.; Bychkova, Valentina E.; and Ptitsyn, Oleg B., ""Domain" Coil-globule Transition in Homopolymers" (1995). Molecular Medicine Faculty Publications. 633.