Patent ID: 7833799

Claim:
A method of performing protein analysis on a plurality of proteins comprising: a. providing a plurality of different labeled proteins from two or more different samples, wherein the proteins within a sample are labeled with the same optical labeling molecule, and the proteins within a different sample are labeled with a different optical labeling molecule, wherein each optical labeling molecule comprises: i. a different zwitterionic dye moiety comprising at least one positive or at least one negative charge moiety added to obtain a net neutral charge, wherein the positive charge moiety is selected from a group consisting of a quaternary ammonium group and a guanidinium group, wherein the positive charge moiety is not titratable between the pH of 3-12, and wherein the negative charge moiety is selected from the group consisting of a sulfonate group and a sulfate group, wherein the negative charge moiety is not titratable between the pH of 3-12; ii. a titratable group moiety, wherein the titratable group is a tertiary amine which closely approximates the pK of the group removed from the protein by reaction with a functional linker; iii. an optional cleavable moiety; and iv. a functional linker moiety; b. mixing and separating simultaneously the plurality of different labeled proteins from different samples; and c. determining the presence or absence of each of the different labeled proteins in each sample.