label: sphing-4-enine + 2 S-adenosyl-L-methionine => N,N-dimethylsphing-4-enine + 2 S-adenosyl-L-homocysteine + 2 H(+)
label_lc: sphing-4-enine + 2 s-adenosyl-l-methionine => n,n-dimethylsphing-4-enine + 2 s-adenosyl-l-homocysteine + 2 h(+)