The ability to measure 7,000 proteins at once starts with

Exquisite Specificity

"The SomaScan [assay] also has a two-step approach to specificity that is sometimes forgotten by non-experts...between these two steps, the assay turns out to be quite highly specific"
Peter Ganz
Director of the Center of Excellence in Vascular Research at the Zuckerberg San Francisco General Hospital and Professor of Medicine at the University of California in San Francisco

Why Aptamers?

Shape specificity:

By using uniquely modified DNA with hydrophobic functional groups, our SOMAmer® reagents achieve a greater degree of shape matching, enabling discernment between nearly identical proteins.

Slow off-rates:

SOMAmer reagents are selected for slow off-rates when correctly bound to their intended target to ensure that correct proteins remain preferentially bound during rigorous washing.

Polyanionic competition:

Polyanionic competitors are used to universally prevent rebinding of transient, non-specific interactions. There is no such universal competitor for antibodies.

X=ray crystal structure of a SOMAmer reagent bound to PDGF-BB
X-ray crystal structure of a SOMAmer reagent bound to PDGF-BB. Modifications to the bases are shown in purple, and the DNA backbone and unmodified bases are in teal.
Graph showing typical dissociation for a SOMAmer reagent (in this case targeting C3)

What evidence do we have that SOMAmer reagents are specific?

What are the advantages of shape-specific proteomics?

How does exquisite specificity enable 7,000 protein measurements?