- Designed amino acid ATRP initiators for the synthesis of biohybrid materials
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A synthetic strategy to prepare peptide-polymer conjugates with precise sites of attachment is described. Amino acids modified with atom transfer radical polymerization (ATRP) initiators for the polymerization of styrenes and hacrylates were prepared. Fmoc-4-(1-chloroethyl)-phenylalanine (5) was synthesized in four steps from Fmoc-tyrosine. HATU-mediated amidation with glycine-OMe resulted in dipeptide (6). The initiator was effective for Cu(I)/bipyridine mediated bulk polymerization of styrene. Kinetic studies indicated a controlled polymerization, with high conversion (97%), and a polydispersity index (PDI) of 1.25. Fmoc-O-(2-bromoisobutyryl)-serine tert-butyl ester (10) was synthesized from Fmoc-Ser(OTrt)-OH in three steps. This initiator was employed in the ATRP of 2-hydroxyethyl methacrylate (HEMA), and kinetic studies indicated a controlled polymerization. Different monomer to initiator ratios resulted in poly-(HEMA) of different molecular weights and narrow PDIs (1.14-1.25). Conversions were between 70 and 99%. HEMA modified with N-acetyl-D-glucosamine (GlcNAc) was also polymerized to 84% conversion and the resulting PDI was 1.19. The t-butyl ester protecting group of 10 was removed, and the resulting amino acid (11) was incorporated into VM(H)VVQTK by standard solid-phase peptide synthesis. Polymerization resulted in the glycopolymer-peptide conjugate in 93% conversion and a PDI of 1.14.
- Broyer, Rebecca M.,Quaker, Grace M.,Maynard, Heather D.
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p. 1041 - 1047
(2008/09/20)
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- Caged phospho-amino acid building blocks for solid-phase peptide synthesis
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Three 1-(2-nitrophenyl)ethyl-caged phosphoamino acids have been synthesized for use in standard Nα-fluorenylmethoxycarbonyl-based solid-phase peptide synthesis (SPPS). The most common naturally occurring phosphoamino acids, serine, threonine, and tyrosine, were prepared as protected caged building blocks by modification with a unique phosphitylating reagent. In previous work, caged phospho-peptides were made using an interassembly approach (Rothman, D. M.; Vazquez, M. E.; Vogel, E. M.; Imperiali, B. Org. Lett. 2002, 4, 2865-2868). However, this technique is limited to creating peptides without oxidation sensitive residues C-terminal to the amino acid to be modified and the methodology involves synthetic manipulations on the solid phase that may limit the utilization of the methodology. Herein we report the facile synthesis of N-α-Fmoc-phospho(1-nitrophenylethyl-2-cyanoethyl)-L-serine 1, N-α-Fmoc-phospho(1-nitrophenylethyl-2-cyanoethyl)-L-threonine 2, and N-α-Fmoc-phospho(1-nitrophenylethyl-2-cyanoethyl)-L-tyrosine 3. These building blocks allow the synthesis of any caged phospho-peptide sequence using standard Fmoc-based SPPS procedures.
- Rothman, Deborah M.,Vazquez, M. Eugenio,Vogel, Elizabeth M.,Imperiali, Barbara
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p. 6795 - 6798
(2007/10/03)
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