Biomedical Engineering Reference
In-Depth Information
FIGURE11.4
DNA-encoded chemical library by stepwise peptide/oligonucleotide synthesis
on the same reaction bead. (a) Monomeric chemical compounds and coding-oligonucleotide
tags are attached on the same solid support in an alternating fashion. The library can, in
principle, be probed for binding to a selected target protein of interest. Here “aa” represents the
different amino acids, and “tag” refers to a DNA sequence encoding the corresponding amino
acid added in the stepwise procedure. (b) Schematic representation of the support by Brenner
and Lerner and by Janda in the first practical implementation of the methodology. The cleavable
linker enables easy detachment of the oligonucleotide-encoded peptide after synthesis, while
O-DMT-protected serine and
N
-Fmoc-protected lysine allows for the bidirectional synthesis
of oligonucleotide and peptide sequences. (c) Leucine-enkephalin pentapeptide (YGGFL)
oligonucleotide conjugate after cleavage from beads. The conjugate was shown to bind to the
anti-leucine-enkephalin antibody 3-E7 as efficiently as the reference peptide (
K
D
=
7.1 nM).
Notably, the cognate oligonucleotide code could be amplified by standard PCR.
In the same theoretical article, Brenner and Lerner anticipated a split-pool-based
combinatorial approach for the construction of DNA-encoded libraries, in which
monomeric chemical compounds and coding-oligonucleotide tags are attached on
the same solid support in an alternating fashion (Figure 11.4a) [47]. This strategy
was demonstrated experimentally in collaboration with Janda's group in 1993 [48].
To test the feasibility of a stepwise peptide/oligonucleotide synthesis on the same
reaction bead, a functionally active leucine-enkephalin pentapetide (YGGFL) was
synthesized in five rounds of alternated synthesis [48]. Controlled-pore glass beads,
serving as structural linkers between the nascent chemical molecules and the coding
oligonucleotides, were used to facilitate oligonucleotide synthesis. The solid support
