Two-dimenstional electrophoretic separation of carbohydrates

A method for assaying for the affinity of a protein for a carbohydrate in a mixture of carbohydrates, comprising the steps of:

• reacting the mixture of carbohydrates with a 1-amino-4-naphthalene sulfonic acid to form carbohydrate and ANSA conjugates;
• subjecting the carbohydrate and ANSA conjugates to first-dimensional gel electrophoresis in a first direction for a sufficient period of time to form separate bands of conjugates in the first dimensional electrophoresis gel;
• removing a band of conjugates from the first dimensional electrophoresis gel;
• subjecting the removed band of conjugates to a second-dimensional gel electrophoresis in a second direction, which is substantially perpendicular to the first direction, for a sufficient period of time to form separate bands of conjugates in the second-dimensional electrophoresis gel;
• electro-blotting the separate bands of conjugates in the second-dimensional electrophoresis gel onto the surface of a membrane;
• and
• contacting the surface having the conjugates thereon with labeled probes to determine the affinity of the probes to bind to carbohydrates on the membrane.