A simple solid phase, peptide-based fluorescent assay for the efficient and universal screening of HRV 3C protease inhibitors

Peptide-based biosensors

Peptides have been used as components in biological analysis and fabrication of novel biosensors for a number of reasons, including mature synthesis protocols, diverse structures and as highly selective substrates for enzymes. Bio-conjugation strategies can provide an efficient way to convert interaction information between peptides and analytes into a measurable signal, which can be used for fabrication of novel peptide-based biosensors. Many sensitive fluorophores can respond rapidly to environmental changes and stimuli manifest as a change in spectral characteristics, hence environmentally-sensitive fluorophores have been widely used as signal markers to conjugate to peptides to construct peptide-based molecular sensors. Additionally, nanoparticles, fluorescent polymers, graphene and near infrared dyes are also used as peptide-conjugated signal markers. On the other hand, peptides may play a generalist role in peptide-based biosensors. Peptides have been utilized as bio-recognition elements to bind various analytes including proteins, nucleic acid, bacteria, metal ions, enzymes and antibodies in biosensors. The selectivity of peptides as an enzymatic substrate has thus been utilized to construct enzyme sensors or enzyme-activity sensors. In addition, progress on immobilization and microarray techniques of peptides has facilitated the progress and commercial application of chip-based peptide biosensors in clinical diagnosis.

Synthesis and evaluation of 9-deoxy analogues of (-)-thysanone, an inhibitor of HRV 3C protease

9-Deoxy analogues of the HRV 3C protease inhibitor (-)-thysanone display better inhibitory properties than the natural product, inferring the C9-OH hinders binding to the enzyme.

Synthesis of the 2-methylene analogue of the HRV 3C protease inhibitor thysanone (2-carbathysanone)

The Human Rhinovirus (HRV) is the major aetiological agent for the common cold, for which only symptomatic treatment is available. HRV maturation and replication is entirely dependent on the activity of a virally encoded 3C protease that represents an attractive target for the development of therapeutics to treat the common cold. Herein we report the synthesis and biological evaluation of the 2-methylene analogue of the HRV 3C protease inhibitor (-)-thysanone (1) namely 2-carbathysanone (2), in an attempt to decipher the structural features in the natural product that are responsible for the 3C protease activity. 2-Carbathysanone (2) (and related analogues (±)-cis-23, (±)-cis-30, (±)-31) did not inhibit HRV 3C protease, indicating that the lactol functionality present in (-)-thysanone (1) is a critical structural feature required for inhibition.

Prevention of cell death by antibodies selected from intracellular combinatorial libraries

One of the most important phenotypes in biology is cell death. One way to probe the mechanism(s) of cell death is to select molecules that prevent it and learn how this was accomplished. Here, intracellular combinatorial antibody libraries were used to select antibodies that protected cells from killing by rhinovirus infection. These rare antibodies functioned by inhibiting the virus-encoded protease that is necessary for viral maturation. Snapshots of the selection process after each round could be obtained by deep sequencing the ever-enriching populations. This detailed analysis of the enrichment process allowed an interesting look at a "test tube" selection process that pitted two replicating systems against each other. Thus, initially a minority of cells containing protective antibodies must compete against a majority of unprotected cells that continue to produce large amounts of virus.