Sialic acids of rat spinal cord. WAX-HPLC
separates glycans on
the basis of charge, and fetuin-N was used as a reference
standard. Neutral N-glycans (77%); mono-charged (12%); di-charged
(4%); tri-charged (1%); tetra-charged (1%); unidentified highly charged
N-glycan species (5%); 2AB, excess 2AB label; (A) UND, undigested;
(B) ABS, ABS (sialidase) digested. The dashed line indicates the zoomed
region. (C) Reference standard for DMB analysis. (D) Neu5Ac is the
most common type of sialic acid in the rat spinal cord, with minor
amounts of Neu5Gc- and Neu5xAc2-type sialic acids. Sialic acids were
released from spinal cord glycans by hydrolysis and separated on the
basis of chemical structure. Peak 1, Neu5Gc; peak 2, Neu5Ac; peak
3, Neu5,7Ac2; peak 4, Neu5Gc9Ac; peak 5, Neu5,8Ac2; peak 6, Neu5,9Ac2;
and peak 7, Neu5,x,xAc3, where x is an unknown position; * contaminant
peak. Note that DMB analysis was performed on total spinal cord glycans,
and WAX-HPLC on N-glycans.