Encoded combinatorial libraries for the construction of cyclic peptoid microarrays

Abstract

A "one bead two compound" approach to the synthesis of encoded cyclic peptoid libraries is reported.

Figure 1

Schematic view of the general strategy employed to create a library in which each bead carries a cyclic peptoid and an analogous linear encoding strand. Only the cyclic molecule contains a thiol and thus will couple to a maleimide-activated glass slide.

Figure 2

Synthesis of the encoded cyclic peptoid library via the one bead two compound strategy. The amines employed in the sub-monomer peptoid synthesis are shown at the bottom of the figure (one of the amines in 1,4-diaminobutane and a hydroxyl group in ethanolamine were protected).

Figure 3

Attachment of Cys-containing cyclic peptoid to a maleimide-activated glass slide. A. General structure of the cyclic and linear molecules made on each bead before cleavage and deprotection of the thiol side chain. Below: Sequences of the variable regions of five peptoids picked for the spotting experiment. B. Fluorescent image of microarrays in which each of the five peptoids have been spotted onto the activated surface. A DMSO solution of each peptoid (≈ mM) was spotted two times, the solution was diluted three-fold, spotted again, etc. After washing and drying, the arrays were hybridized with Cy3-conjugated streptavidin, washed and the slide was scanned with a fluorescence scanner (see ref. for details). The spots are false-colored green. C. The Cys is essential for retention of the peptoid on the microarray. Two peptoids were synthesized. Each had the sequence Fluorescein-Nlys-Nser-Nleu-Nser-Nall-Npip-Nlys-Nlys. One peptoid also contained a C-terminal cysteine, while the other did not. The two peptoids were spotted onto a maleimide-activated glass slide. After washing, the slide was scanned using a fluorescence scanner. The fluorescence intensity is false-colored blue.