Ligand Identification (Bead blot)

Prolias uses specialized ProSpectrum Libraries™ (PSL-1) of ligands to identify specific ligands that can be used to purify proteins or as targets in a technology called the Bead blot (US Patent 7,217,507). In this method, ligands are identified to proteins contained in their natural state, without purification or derivization (diagram of the bead blot). This enables ligands to be identified under conditions in which the ligand will be used in practice, and decreases false positive hits. The starting material is incubated with library (A) and the beads are immobilized in a matrix (B). Bound proteins are eluted from the beads by capillary action of a transfer buffer (C2) and captured on a protein-binding membrane (C1). All of the proteins that elute under the particular transfer conditions are captured on the membrane. The location of the protein of interest is detected on the membrane(D); the membrane and gel are aligned (E) and the bead that bound the protein is identified. The bead can be collected, the ligand sequenced and scaled up, and the protein purified on the same chromatography resin backbone as it was originally identified.

Ligands have been identified to a number of targets, including:

• Fibrinogen
• CRP in blood and plasma
• IL-2
• Prion protein - the Bead blot was used to identify ligands that remove infectivity from blood. One of these has been developed into a CE-marked class IIB device, the P-Capt™ filter marketed by MacoPharma
• and more