Mass spectrometric assignment of Smith degradation glycopeptides derived from ribonuclease B.
We established a method to determine the glycosyl linkage structure by a combination of Smith degradation and liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (LC-ESI-Q-TOF-MS) and tandem MS (MS/MS). To assign the sugar linkage of N-glycoprotein, we employed a typical ribonuclease B containing oligosaccharides (Man5-9GlcNAc2). Tryptic digestion of ribonuclease B provided a mixture of high-mannose glycopeptides consisting of the four amino acids, Asn34-Leu-Thr-Lys37 (NLTK, T6). The mixture of glycopeptides was separated by high-performance liquid chromatography (HPLC) in a reversed phase column and was characterized by ESI-Q-TOF-MS and MS/MS. Comparison of the data with and without Smith degradation allowed us to make reasonable assignments to support such linkage patterns as (1-->2), (1-->3), (1-->6) and their multiples. These assignments were limited to six mannoses or lower due to the unstable nature of the higher derivatives. This method should be applicable to determine the linkage pattern of an unknown glycoprotein in about a 6-microgram amount.
Laboratory of Organic Chemistry, School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Suthasinee
S
Pitchayawasin
Minoru
M
Isobe
D000596:Amino Acids / Q000032:analysis; D001894:Borohydrides / Q000737:chemistry; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D006020:Glycopeptides / Q000737:chemistry*; D008358:Mannose / Q000032:analysis; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010504:Periodic Acid / Q000737:chemistry; D012260:Ribonucleases / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014357:Trypsin
D000596:Amino Acids; D001894:Borohydrides; D006020:Glycopeptides; D010504:Periodic Acid; C025364:sodium borohydride; C009288:metaperiodate; D012260:Ribonucleases; C029600:ribonuclease B; D014357:Trypsin; D008358:Mannose