an N-acyl-sphingoid base + D-galactose => a beta-D-Gal-(1<->1')-ceramide + H2O
an n-acyl-sphingoid base + d-galactose => a beta-d-gal-(1<->1')-ceramide + h2o
an N-acyl-sphingoid base + D-galactose => a beta-D-Gal-(1<->1')-ceramide + H2O
an n-acyl-sphingoid base + d-galactose => a beta-d-gal-(1<->1')-ceramide + h2o