While phage antibody technology has generally been used to obtain large numbers of specific capture molecules, the technology is not applicable to all targets and is highly protected by third party intellectual property. Pastel therefore decided to create its own capture molecule library based on a totally novel human scaffold molecule. This was selected for a number of characteristics tailored to its use for the InVenio™ biomarker discovery & validation platform.

The scaffold molecules that have been pre-engineered as capture molecules are based on low molecular weight human proteins and therefore make them amenable to use as therapeutics.

They have many advantages over other scaffolds:
(i) the target molecule is not required for either immunisation or selection techniques
(ii) the capture molecules are significantly smaller than antibodies having molecular weights of the order 19Kda and therefore demonstrate far better mass transfer and bioavailability
(iii) they are composed of a single monomeric polypeptide chain having no cysteine bridges or post-translational modifications
(iv) this ensures that they are easily produced in prokaryotic expression systems providing significant cost savings and inexpensive product.

The binding site of the human scaffold molecule is well characterised which has allowed Pastel's scientists to rationally re-engineer the molecule to recognise prescribed targets with high affinity and specificity.

Both the amino and carboxy termini are also effectively free so that they can be functionally fused to effector molecules or probes.

Scaffold molecule showing the underlying structure - ribbon format