This is the first report of the synthesis of a well-defined glycopolymer by free radical polymerization. N-(p-vinylbenzyl)-[O-β-d-galactopyranosyl-(1→4)]-d-gluconamide (VLA), a styrene derivative with an oligosaccharide moiety, was polymerized in N,N-dimethylformamide solution at 90 °C by the nitroxide-mediated free radical polymerization technique. Acetylated VLA gave polymers with a molecular weight from about 2000 to 40 000, an M w/M n ratio of about 1.1 in all cases, and a conversion of up to about 90%, where M w and M n are the weight- and number-average molecular weights. Indispensable for this success were (1) the use of di-tert-butyl nitroxide (DBN) rather than other nitroxides such as TEMPO, (2) the acetylation of VLA, and (3) the use of a radical initiator DCP (dicumyl peroxide) as an accelerator. DBN provided a well-controlled polymerization of VLA at 90 °C (VLA becomes unstable at higher temperatures, e.g., >120 °C). The acetylation effectively prevented the chain transfer that leads to dead polymers and broad polydispersities. DCP remarkably accelerated the rate of polymerization (the rate of chain extension), which otherwise was impractically slow, without causing any appreciable broadening of polydispersity.

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Vimentin and desmin are intermediate filament proteins found in various mesenchymal and skeletal muscle cells, respectively. These proteins play an important role in the stabilization of the cytoplasmic architecture. Here, we found, using artificial biomimicking glycopolymers, that vimentin and desmin possess N-acetylglucosamine (GlcNAc)-binding lectin-like properties on the cell surfaces of various vimentin- and desmin-expressing cells such as cardiomyocytes and vascular smooth muscle cells. The rod II domain of these proteins was demonstrated to be localized to the cell surface and to directly bind to the artificial biomimicking GlcNAc-bearing polymer, by confocal laser microscopy and surface plasmon resonance analysis. These glycopolymers strongly interact with lectins and are useful tools for the analysis of lectin-carbohydrate interactions, since glycopolymers binding to lectins can induce the clustering of lectins due to multivalent glycoside ligand binding. Moreover, immunocytochemistry and pull-down assay with His-tagged vimentin-rod II domain protein showed that the vimentin-rod II domain interacts with O-GlcNAc proteins. These results suggest that O-GlcNAc proteins might be one candidate for physiological GlcNAc-bearing ligands with which vimentin and desmin interact. These findings demonstrate a novel function of vimentin and desmin that does not involve stabilization of the cytoplasmic architecture by which these proteins interact with physiological GlcNAc-bearing ligands such as O-GlcNAc proteins on the cell surface through their GlcNAc-binding lectin-like properties.

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Kinetic measurements of the interaction between an oligosaccharide and various lectins were performed using a biosensor based on surface plasmon resonance (SPR). A glycopeptide, prepared from asialofetuin and having a nearly homogeneous N-linked sugar chain, was immobilized on the surface of a sensor chip via the amino groups of its peptide moiety. The interactions of this bound glycopeptide with six lectins [Sambucus sieboldiana lectin, Maackia amurensis lectin, Aleuria uuruntia lectin, Ricinus communis agglutinin-1 20 (RCA,,,), Datura stramonium lectin (DSA) and Phaseolus vulgaris leukoagglutinating lectin] were monitored in real-time with the change in the SPR response. Of these lectins, only RCA,,, and DSA showed an increase in the SPR response, indicating that these two lectins bound specifically to the immobilized glycopeptide. The other lectins did not show any significant changes in the SPR response. These results are in good agreement with the binding specificity previously demonstrated with affinity chromatography. The association-rate constant (k,,,) and the dissociation-rate constant (k,,,,) for the glycopeptide-RCA,,, interaction were 3.4X lo5 M-' s-' and 2.1 X lop3 s-', respectively. The k,,, and kdlSs determined for DSA were S.7X105 M-' s-' and 1.3X 10-3 sp', respectively. Furthermore, the relative binding molar ratio to the glycopeptide was three times higher for RCA,,, than for DSA, suggesting that this sugar chain possesses three binding sites for RCA,,, and one for DSA. These parameters are expected to provide useful information for defining the interaction between oligosaccharides and lectins.Many aspects of the interactions between lectins and glycoproteins have been studied, especially regarding the recognition of molecules. These interactions have been used for the detection of the oligosaccharides of glycoproteins. In conventional methods, the recognition and adsorption properties of lectins with the specific sugar residues of glycoproteins are used for chromatographic purification and electrophoretic analytical techniques [l-31. However, it is not easy to elucidate the reaction mechanisms. Furthermore, for kinetic studies of the interactions between lectins and glycoproteins, it is usually necessary to label the molecules, either lectins or carbohydrates [4, 51. This has been a time-consuming step in these studies. The method introduced here requires no labeling, and the interaction phenomena of biological molecules can be monitored directly by the surface plasmon resonance (SPR).The phenomena of SPR was studied by Otto [6] and Kretschman and Raether [7], and it was used as a chemical Correspondence to Y. Shinohara,

We report a useful synthetic method of polypeptides using a series of urethane derivative of α‐amino acids (l‐leucine, l‐phenylalanine, l‐valine, l‐alanine, l‐isoleucine, l‐methionine), which are readily synthesized by N‐carbamoylation of tetrabutylammonium salts of α‐amino acids with diphenyl carbonate. Heating these urethane derivatives in N,N‐dimethylacetamide in the presence of n‐butylamine successfully gave the corresponding polypeptides with well‐defined structures through polycondensation with the elimination of phenol and CO2. The matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry investigation showed that the resulting polypeptides had an n‐BuNH2‐incorporated initiating end and an amino group at propagating end. These results strongly indicated that primary amines served as an initiator in this polycondensation system. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3726–3731

Polymethionine(oxide)s were readily synthesized through polycondensation with amines, accompanying the elimination of phenol and CO2 and used as antifouling polymer against biological matters.

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