Detection of Proteins by On‐Column, Non‐Covalent Labeling with NanoOrange During Capillary Zone Electrophoresis

Abstract

To avoid prior derivatization of proteins with fluorescent reagents, on‐column labeling of non‐covalent dye NanoOrange on proteins was evaluated with sodium dodecyl sulfate (SDS) as an additive using laser induced fluorescence (LIF) monitoring in capillary electrophoresis (CE). Performance of NanoOrange in buffer solutions of various pH values was tested. Acidic buffer solution was found to be unsuitable for on‐column NanoOrange labeling. SDS enhanced the fluorescence intensities of basic proteins with high pI values. The fluorescence intensities of protein solutions with or without SDS additives were compared using a fluorescence spectrophotometer. The applicability of on‐column labeling and detection of staphylococcal enterotoxin B was also demonstrated. This on‐column labeling method provides a rapid, direct, widely applicable technique for protein studies.

Keywords:

• Capillary electrophoresis
• Proteins
• Laser induced fluorescence
• NanoOrange
• Non‐covalent labeling