A CMP-NeuAc:GM1 α2-3sialyltransferase (GD1a synthase, 2.4.99.2) has been purified from the Triton extract of rat brain. The enzyme was purified and resolved by affinity chromatography on CDP-Sepharose column by a linear NaCl gradient elution. Final purification was achieved by elution from a ‘GM1-acid’-Sepharose column. SDS-PAGE of the enzyme revealed a single protein band with an apparent M r 44 kDa. It catalyzed specifically the sialylation of GD1b, GM1 and asialo-GM1. Enzyme products were identified by TLC in three different solvent systems, The K m value for GM1 was 7.5 × 10−2 M, and for CMP-NeuAc it was 6.5 × 10−5 M.
