[Label-free quantitative peptidomics-based analysis on glycopeptides in deerhorn gelatin and deer-hide gelatin]

Nano-LC-MS/MS was used to analyze trypsin digested deer-horn gelatin( DCG) and deer-hide gelatin( DHG) samples.The glycopeptides in DCG and DHG were quantified by Label-free quantitative( LFQ) peptidomics,on the basis of which the glycopeptides with significant difference in DCG and DHG were determined. As a result,5 736 peptides were identified from DCG samples,including 213 galactosyl-hydroxylysine containing peptides( Gal-Hyl-peptides) and 102 glucosyl-galactosyl-hydroxylysine containing peptides( Glc-Gal-Hyl-peptides),while 6 836 peptides were identified from DHG samples,among which there were 250 Gal-Hyl-peptides and 98 Glc-Gal-Hyl-peptides. With over 3-fold peak area difference and highly significant intergroup difference( P < 0. 01) as the screening criteria,444 differential peptides were determined in DCG and DHG,including 16 Gal-Hyl-peptides and 5 Glc-Gal-Hyl-peptides. Then XIC peak shapes,standard deviation of peak area,and fold change were applied for further screening and 5 glycopeptides with significant differences in DCG and DHG were confirmed,which could serve as potential biomarkers for distinguishing DCG and DHG. The present study provided ideas and strategies for the in-depth investigation on the discrimination of DCG and DHG and is of good theoretical significance and application value for the further research on chemical constituents and quality control of gelatin derived Chinese medicinals.

[Analysis of hydroxylation and O-glycosylation on lysine sites in deer-hide gelatin]

Nano-LC MS/MS was used to analyze trypsin digested deer-hide gelatin(DHG) samples, hydroxylation and O-glycosylation on lysine sites of DHG were comprehensive identified by using PEAKS Studio software. The sites, sorts and amounts of hydroxylation and O-glycosylation on Type Ⅰ collagen α1 chain(COL1 A1) and α2 chain(COL1 A2) of DHG were revealed. As a result, 5 284 peptides were identified from DHG samples, which were mainly from COL1 A1 and COL1 A2. Among these peptides, there were 449 peptides with hydroxylysine, 442 with galactosyl-hydroxylysine, 449 with glucosyl-galactosyl-hydroxylysine. The major modified sites of hydroxylation and O-glycosylation in DHG were shown as follow: α1-9 N and α2-5 N in N-telopeptides, α1-87, α1-174, α1-930, α2-87, α2-174, α2-933 in triple helix domain, and α1-16 C in C-telopeptides. These hydroxylation and O-glycosylation were correlated with the formation and stability of collagen molecules and collagen fibrils. It is feasible for the collagens and peptides dissolving from deer skin collagen fibrils under high temperature and pressure decocting, high temperature and pressure also might destroy inter-molecular covalent cross-linking and help those glycol-peptides formations. The present study provided ideas and strategies for the in-depth investigation on DHG chemical constituents, and showed good theoretical significance and application value.