Provided are methods and compositions which are useful for separating, isolating, detecting, and quantifying compounds of interest which have been modified chemically, enzymatically or catalytically from other compounds which have not been so modified. The modifications may take the form of functional groups which are gained, lost or retained by the compounds of interest.

Provided are methods and compositions which are useful for separating, isolating, detecting, and quantifying compounds of interest which have been modified chemically, enzymatically or catalytically from other compounds which have not been so modified. The modifications may take the form of functional groups which are gained, lost or retained by the compounds of interest.

The present disclosure provides methods of selectively label an amino acid residue on a peptide by replacing a post translational modification with a labeling moiety and sequencing the peptide to obtain the location of the amino acid residue and the identity of the post translational modification. In some aspects, the disclosure also provides methods of identifying the position, quantity, the identity of a post translational modification, or any combination thereof, in peptides which may be used for therapeutic purposes.

The invention relates to an enzymatically responsive product that includes an amino acid residue conjugated to a magnetic particle, wherein the amino acid residue is phosphorylated or sulfated or comprises an ester-moiety linked via peptide bond. Compositions containing the enzymatically responsive product, and the use thereof for separating distinct types of mammalian cells (e.g., cancer cells from normal cells), for treating a cancerous condition, and imaging cancer cells are also disclosed.

Provided are methods and compositions which are useful for separating, isolating, detecting, and quantifying compounds of interest which have been modified chemically, enzymatically or catalytically from other compounds which have not been so modified. The modifications may take the form of functional groups which are gained, lost or retained by the compounds of interest.

The present invention relates to methods for detecting protein S-sulfinylation and S-sulfinylation within thiol groups in proteins, metabolites, or materials.

Provided are methods and compositions which are useful for separating, isolating, detecting, and quantifying compounds of interest which have been modified chemically, enzymatically or catalytically from other compounds which have not been so modified. The modifications may take the form of functional groups which are gained, lost or retained by the compounds of interest.

The present invention relates to methods for detecting protein S-sulfinylation and S-sulfinylation within thiol groups in proteins, metabolites, or materials.

The invention relates to an enzymatically responsive product that includes an amino acid residue conjugated to a magnetic particle, wherein the amino acid residue is phosphorylated or sulfated or comprises an ester-moiety linked via peptide bond. Compositions containing the enzymatically responsive product, and the use thereof for separating distinct types of mammalian cells (e.g., cancer cells from normal cells), for treating a cancerous condition, and imaging cancer cells are also disclosed.