Biomedical Engineering Reference
In-Depth Information
(a)
SM
SM
SM
PNA
SM
SM
(b)
Biotin
Avidin
SM
(c)
SM
C
8
F
17
FIGURE 13.3
Selected examples of noncovalent immobilization approaches in SMM: (a)
small molecules with a PNA tag hybridized onto a DNAmicroarray; (b) small molecules with a
biotin tag immobilized onto an avidin-coated slide surface; (c) small molecules with a fluorous
tag absorbed onto a fluorinated glass slide.
By exploiting the strong interaction between DNA and peptide nucleic acid (PNA),
Winssinger et al. developed another newmethod for the preparation of SMMs (Figure
13.3a) [31]. In an early experiment, the group linked cathepsin inhibitors covalently
with a PNA tag whose sequence encodes the identity of the inhibitors. The advantage
of a PNA tag lies in its synthetic flexibility and resistance to degradation. These
small molecule-PNA conjugates were then allowed to incubate with cathepsin. After
passing through size-exclusion chromatography, the small molecule-PNA conjugates
that bind to cathepsin were isolated and hybridized onto a DNA array to reveal their
identity. The method has proved to be highly sensitive. It could detect as little as
0.4 pmol of cathepsin. The approach was subsequently extended to profile protease
activity in crude cell lysates and dust mite extracts [32,33].
