J. D. R. Kramer

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Conformation-switchable glycopolypeptides were prepared by the living polymerization of glycosylated L-cysteine-N-carboxyanhydride (glyco-C NCA) monomers. These new monomers were prepared in high yield by coupling of alkene-terminated C-linked glycosides of D-galactose or D-glucose to L-cysteine using thiol-ene "click" chemistry, followed by their(More)
The preparation of new glycosylated-L-lysine-N-carboxyanhydride (glyco-K NCA) monomers is described. These monomers employ C-linked sugars and amide linkages to lysine for improved stability without sacrificing biochemical properties. Three glyco-K NCAs were synthesized, purified, and found to undergo living polymerization using transition metal initiation.(More)
We describe the application of flash column chromatography on silica gel as a rapid and general method to obtain pure α-amino acid-N-carboxyanhydride (NCA) monomers, the widely used precursors for the synthesis of polypeptides, without the need for recrystallization. This technique was effective at removing all common impurities from NCAs and was found to(More)
We report the development of a new "click"-type reaction for polypeptide modification based on the chemoselective alkylation of thioether groups in methionine residues. The controlled synthesis of methionine polymers and their alkylation by a broad range of functional reagents to yield stable sulfonium derivatives are described. These "methionine click"(More)
Mucins are a family of secreted and transmembrane glycoproteins characterized by a massive domain of dense O-glycosylation on serine and threonine residues. Mucins are intimately involved in immunity and cancer, yet elucidation of the biological roles of their glycodomains has been complicated by their massive size, domain polymorphisms, and variable(More)
We report the design and synthesis of poly(S-alkyl-L-homocysteine)s, which were found to be a new class of readily prepared, multiresponsive polymers that possess the unprecedented ability to respond in different ways to different stimuli, either through a change in chain conformation or in water solubility. The responsive properties of these materials are(More)
Reagents were developed to allow chemoselective tagging of methionine residues in peptides and polypeptides, subsequent bioorthogonal functionalization of the tags, and cleavage of the tags when desired. This methodology can be used for triggered release of therapeutic peptides, or release of tagged protein digests from affinity columns.
We have developed a facile, scalable method for preparation of enzyme-responsive copolypeptide vesicles that requires no protecting groups or expensive components. We designed amphiphilic copolypeptides containing segments of water-soluble methionine sulfoxide, M(O), residues that were prepared by synthesis of a fully hydrophobic precursor diblock(More)
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