Demonstration of carbohydrate structures in malignant melanoma tyrosinase

Electrophoretic studies on malignant melanoma extracts before and after treatment with neuraminidase revealed that tyrosinase is a glycoprotein containing N-acetyl-neuraminic acid. Double diffusion tests using Concanavalin A and the lectin from Ricinus communis show that the carbohydrated chain of tyrosinase contains D-mannose as a sugar unit located within the carbohydrate chain. The terminal neuraminic acid groups are linked to D-galactose. The enzymatic activity of tyrosinase is not inhibited by Concanavalin A.