1431699-56-7Relevant articles and documents
Synthesis and Characterization of Nitroaromatic Peptoids: Fine Tuning Peptoid Secondary Structure through Monomer Position and Functionality
Fowler, Sarah A.,Luechapanichkul, Rinrada,Blackwell, Helen E.
experimental part, p. 1440 - 1449 (2009/07/30)
N-Substituted glycine oligomers, or peptoids, have emerged as an important class of foldamers for the study of biomolecular interactions and for potential use as therapeutic agents. However, the design of peptoids with well-defined conformations a priori remains a formidable challenge. New approaches are required to address this problem, and the systematic study of the role of individual monomer units in the global peptoid folding process represents one strategy. Here, we report our efforts toward this approach through the design, synthesis, and characterization of peptoids containing nitroaromatic monomer units. This work required the synthesis of a new chiral amine building block, (S)-1-(2-nitrophenyl)ethanamine (s2ne), which could be readily installed into peptoids using standard solid-phase peptoid synthesis techniques. We designed a series of peptoid nonamers that allowed us to probe the effects of this relatively electron-deficient and sterically encumbered a-chiral side chain on peptoid structure, namely, the peptoid threaded loop and helix. Circular dichroism spectroscopy of the peptoids revealed that the nitroaromatic monomer has a significant effect on peptoid secondary structure. Specifically, the threaded loop structure was disrupted in a nonamer containing alternating V-(S)-1-phenylethylglycine (VVspe) and VVs2ne monomers, and the major conformation was helical instead. Indeed, placement of a single Ns2ne at the N-terminal position of (VVspe)9 resulted in a destabilized form of the threaded loop structure relative to the homononamer (VVspe)9. Conversely, we observed that incorporation of V-(S)-1-(4-nitrophenyl)ethylglycine (VVsnp, a p-nitro monomer) at the VV-terminal position stabilized the threaded loop structure relative to (VVspe)9. Additional experiments revealed that nitroaromatic side chains can influence peptoid nonamer folding by modulating the strength of key intramolecular hydrogen bonds in the peptoid threaded loop structure. Steric interactions were also implicated for the VVs2ne monomer. Overall, this study provides further evidence that aromatic side-chain structure, even if perturbed in a single monomer unit, can strongly influence local peptoid backbone conformation.
Enzymatic synthesis of caged NADP cofactors: Aqueous NADP photorelease and optical properties
Salerno,Magde,Patron
, p. 3971 - 3981 (2007/10/03)
The synthesis of caged NADP analogues 18, 19, and 20 has been accomplished by utilizing the transglycosidase activity of solubilized NAD glycohydrolase (porcine brain) to incorporate caged nicotinamides 2, 3, and 4 into NADP. The synthesis of several nicotinamides modified at the carboxamide with o-nitrobenzyl photolabile groups is demonstrated as well as their potential for enzymatic transglycosidation. These results further demonstrate the feasibility of direct enzymatic transglycosidation of sterically hindered substrates into NAD(P), although high nicotinamide analogue water solubility was found to be a necessary trait for yield enhancement with certain analogues. Caged analogues were surveyed under aqueous conditions for net NADP photorelease, while the UV and fluorescent properties of both analogues and their photobyproducts were assessed for compatibility with systems that rely on optical monitoring of enzyme activity. A highly water-soluble α-methyl-o-nitrobenzyl group 8 was developed for the synthesis of 20 in order to enhance net NADP photorelease. Compound 20 demonstrated a high 75% net NADP photoreleased without substantial UV optical blackening or fluorescent byproducts. Analogues 18 and 19 were shown by ESI/MALDI-MS to photogenerate primarily adducts of NADP with deleterious UV and fluorescent properties. Our work stresses the superior release properties conferred by α-methyl substitution on aqueous carboxamide photorelease from o-nitrobenzyl compounds.
