A review.Chemists at SomaLogic and the University of Colorado Boulder transformed aptamers by creating 20 different side-chain modifications for deoxyuridine triphosphate (dUTP).These modified bases mimic the large, hydrophobic amino acids like tryptophan and phenylalanine, which are often enriched in protein-protein binding sites.When incorporated into aptamers, the modified bases transform aptamers into SOMAmers, or slow off-rate modified aptamers."What SomaLogic has done with these [side-chain modifications] is their single greatest contribution to the field," says Geoff Baird, a pathologist at the University of Washington in Seattle."It is the secret sauce that makes this whole thing work.".Functionally, SOMAmers masquerade as antibodies that also happen to have a unique, identifying DNA sequence at their core.They can potentially act in all the ways that antibodies do-stain biol. samples, block a receptor's action and pull proteins out of complex biol. mixturesSomaLogic has generated SOMAmers specific to 1,129 human proteins, including receptors, cytokines, kinases, growth factors and hormones.Using as little as three drops of blood, or 65 μL, the SOMAscan assay can measure the presence and concentration of those 1,129 proteins simultaneously, down to femtomolar concentrationsThe system can test serum, plasma, urine and cerebrospinal fluid (CSF) samples, as well as cells and tissues.By contrast, the best antibody-based proteomics platforms are limited to surveying 40 or fewer proteins at once.And traditional mass spectrometry-based approaches are not as sensitive.
