N4-glycosyl-L-asparagine Hex2HexNAc2 N4-glycosylated asparagine 730.264404296875 730.66998291015625 844.30731201171875 844.77001953125 modification from Unimod N-linked glycosylation none PSI-MOD C 32 H 52 N 4 O 22 MOD:00521 Hex2HexNAc2 N Hex(2)HexNAc(2) natural C 28 H 46 N 2 O 20 complex glycosylation