Cys-annexin A5 is proprietary technology from MosaMedix BV (e.g. EU patent 1765859, US patent 7511016). The engineered annexin A5 carries a Cysteine on the concave side of the protein, which is opposite to the convex side of the Annexin A5 where its binding to the target occurs. This creates a unique site for coupling of reporter agents (radiolabels, fluorescent labels, MRI) by using simple thiol chemistry. Cys-annexin A5 has also potential for drug delivery. Drugs which are coupled via the Cysteine may be targeted to diseased tissues that have cells with phosphatidylserine exposed on their outer surfaces. The annexin can be internalized and thereby deliver the payload inside the cell.
The proprietary Cys-annexin A5 is currently offered in the Research Market in combination with various fluorescent labels for in vitro – and in vivo imaging applications.