Composition and Methods For Affinity Directed Enrichment of Rare Species

A method for segregating rare species comprising:

• contacting a segregating probe with a sample comprising a mixture of a rare species and a related common species to form a first reaction mixture, wherein the common species is present in at least a 5-fold molar excess over the rare species;
• permitting a first complex comprising the segregating probe and the rare species and a plurality of second complexes comprising the segregating probe and the common species to form in the first reaction mixture;
• contacting the first reaction mixture with a cleavage reagent to form a second reaction mixture, wherein the cleavage reagent results in cleavage of a scissile bond of the segregating probe of the plurality of second complexes while leaving the scissile bond of the segregating probe of the first complex intact;
• contacting the second reaction mixture with a capture species to form a third complex comprising the capture species and the first complex;
• and
• segregating the second complex from the third complex,
• wherein the segregating probe comprises a targeting moiety capable of forming a complex with either of the rare species and the common species, a capture tag capable of forming a complex with the capture species, and wherein the scissile bond is interposed between the targeting moiety and the capture tag.

A segregating probe, comprising:

• a targeting moiety configured to form a complex with rare species and a common species;
• a capture tag;
• a scissile bond interposed between the targeting moiety and the capture tag;
• and
• a protective group,
• wherein the protective group is configured to provide a reduced rate of cleavage of the scissile bond in a first complex comprising the segregating probe and the rare species relative to the rated of cleavage of the scissile bond in a second complex comprising the segregating probe and the common species.

An intermediate for preparation of a segregating probe, comprising:

• a reactive group configured to couple to a targeting moiety, wherein the targeting moiety is configured to form a complex with rare species and a common species;
• a capture tag;
• a scissile bond interposed between the targeting moiety and the capture tag;
• and
• a protective group,
• wherein the protective group is configured to provide a reduced rate of cleavage of the scissile bond in a first complex comprising the segregating probe and the rare species relative to the rated of cleavage of the scissile bond in a second complex comprising the segregating probe and the common species.