Urine extracts were dried under nitrogen, sialated
by reaction with 50 [micro]L of anhydrous pyridine and 50 [micro]L of N,O-bis(trimethylsilyl)trifluoroacetamide + 1% trimethylchlorosilane (BSTFA + TMCS), and then heated at 60[degrees]C for 1 h.
This is a desialated isoform, or [beta]-2 trf, that is useful in differentiating CSF from serum, which typically contains the fully sialated
The molecular masses of these preparations varied between 10 and 15 kDa, which is probably attributable to variable sialated
O-glycosylation on Thr's (7-9).
In their study of hCG[beta] separated from intact urinary hCG, Liu and Bowers (7) detected a range of both sialated
and asialo mono-, bi-, and triantennary N-linked oligosaccharides.