349113-91-3Relevant articles and documents
Synthesis of poly(ethylene oxide) approaching monodispersity
Maranski, Krzysztof,Andreev, Yuri G.,Bruce, Peter G.
, p. 6411 - 6413 (2014/06/24)
Polydispersity in polymers hinders fundamental understanding of their structure-property relationships and prevents them from being used in fields like medicine, where polydispersity affects biological activity. The polydispersity of relatively short-chain poly(ethylene oxide) [(CH 2CH2O2)n; PEO] affects its biological activity, for example, the toxicity and efficacy of PEOylated drugs. As a result, there have been intensive efforts to reduce the dispersity as much as possible (truly monodispersed materials are not possible). Here we report a synthetic procedure that leads to an unprecedented low level of dispersity. We also show for the first time that it is possible to discriminate between PEOs differing in only 1 ethylene oxide (EO) unit, essential in order to verify the exceptionally low levels of dispersity achieved here. It is anticipated that the synthesis of poly(ethylene oxide) approaching monodispersity will be of value in many fields where the applications are sensitive to the distribution of molar mass.
Dependence of effective molarity on linker length for an intramolecular protein-ligand system
Krishnamurthy, Vijay M.,Semetey, Vincent,Bracher, Paul J.,Shen, Nan,Whitesides, George M.
, p. 1312 - 1320 (2007/10/03)
This paper reports dissociation constants and "effective molarities" (Meff) for the intramolecular binding of a ligand covalently attached to the surface of a protein by oligo(ethylene glycol) (EGn) linkers of different lengths (n = 0, 2, 5, 10, and 20) and compares these experimental values with theoretical estimates from polymer theory. As expected, the value of Meff is lowest when the linker is too short (n = 0) to allow the ligand to bind noncovalently at the active site of the protein without strain, is highest when the linker is the optimal length (n = 2) to allow such binding to occur, and decreases monotonically as the length increases past this optimal value (but only by a factor of ～8 from n = 2 to n = 20). These experimental results are not compatible with a model in which the single bonds of the linker are completely restricted when the ligand has bound noncovalently to the active site of the protein, but they are quantitatively compatible with a model that treats the linker as a random-coil polymer. Calorimetry revealed that enthalpic interactions between the linker and the protein are not important in determining the thermodynamics of the system. Taken together, these results suggest that the manifestation of the linker in the thermodynamics of binding is exclusively entropic. The values of Meff are, theoretically, intrinsic properties of the EGn linkers and can be used to predict the avidities of multivalent ligands with these linkers for multivalent proteins. The weak dependence of Meff on linker length suggests that multivalent ligands containing flexible linkers that are longer than the spacing between the binding sites of a multivalent protein will be effective in binding, and that the use of flexible linkers with lengths somewhat greater than the optimal distance between binding sites is a justifiable strategy for the design of multivalent ligands.
Synthesis of oligo(ethylene glycol) toward 44-mer
Ahmed, Saleh A.,Tanaka, Mutsuo
, p. 9884 - 9886 (2007/10/03)
A synthetic method for oligo(ethylene glycol) toward 44-mer (FW = 1956.35) is described. Reiteration of Williamson's ether synthesis and hydrogenation to remove protecting benzyl group affords desired oligo(ethylene glycol) toward 44-mer in moderate yields. The advantages in this method are use of commercially easily available materials as starting materials and procedures avoiding difficulty in purification of the products as much as possible.
