3852105 NeuGc N-glycolylneuraminic acid 101 3073132 NGNA N-glycolylneuraminic acid 20 3852198 NeuGl N-glycolylneuraminic acid 2 1300250 NGc N-glycolylneuraminic acid 1 3784138 NeuNGc N-glycolylneuraminic acid 1