Zhigang Sui

Bioactive components of velvet antlers and their pharmacological properties.

Velvet antler is one of the most important animal medicines, and has been used with a variety of functions, such as anti-fatigue, tissue repair and health promotion. In the past few years, the investigation on chemical compositions, bioactive components, and pharmacological effects has been performed, which demonstrates that velvet antlers could be used as an important health-promoting tonic with great nutritional and medicinal values. This review focuses on the recent advance in studying the bioactive components of velvet antlers.

An activity-maintaining sequential protein extraction method for bioactive assay and proteome analysis of velvet antlers

The exceptional growth rate of velvet antler makes it a valuable model for studying the development of tissues, such as blood vessels, cartilage and bone. Meanwhile, investigating the activities of extracted proteins from velvet antlers promisingly leads to the discovery of new active factors which regulate the development of above-mentioned tissue types. In this study, a novel sequential protein extraction method was developed for proteome profiling and bioactivity study of velvet antlers. Herein, four antler growing tips were pooled to create a proportional pooled sample, and three aliquots of which were extracted in parallel using the developed extraction method. For each sample, proteins were extracted sequentially by saline solvent (0.15M sodium chloride, pH 7.0), mild acid buffer (0.15M acetate buffer, pH 4.0) and mild alkaline buffer (0.15M glycine-sodium hydroxide buffer, pH 10.0) with good bio-compatibility to prevent proteins denaturation. Then STD lysis buffer, containing 4% SDS, 0.1M Tris-HCl and 0.1M DTT, was used to extract hydrophobic proteins. The tryptic digest of each fraction was analyzed by nanoRPLC-ESI-MS/MS in triplicates, with false discovery rate for peptide identification adjusted to 1% to create filtered protein group list. In total, 1423 protein groups were identified, which expanded up to 3 times of the previous published dataset. The relative standard deviation of identified peptide and protein group number for all analyses indicated the good reproducibility of the developed sequential protein extraction method. Additionally, proteins extracted by acid buffer and alkaline buffer showed obvious promoting effect on the proliferation of human umbilical vein endothelial cells. All these results demonstrate that the developed sequential extraction method is efficient for the comprehensive proteome analysis and activity investigation of velvet antlers.

Releasing N-glycan from Peptide N-terminus by N-terminal Succinylation Assisted Enzymatic Deglycosylation

Due to the important roles of N-glycoproteins in various biological processes, the global N-glycoproteome analysis has been paid much attention. However, by current strategies for N-glycoproteome profiling, peptides with glycosylated Asn at N-terminus (PGANs), generated by protease digestion, could hardly be identified, due to the poor deglycosylation capacity by enzymes. However, theoretically, PGANs occupy 10% of N-glycopeptides in the typical tryptic digests. Therefore, in this study, we developed a novel strategy to identify PGANs by releasing N-glycans through the N-terminal site-selective succinylation assisted enzymatic deglycosylation. The obtained PGANs information is beneficial to not only achieve the deep coverage analysis of glycoproteomes, but also discover the new biological functions of such modification.

A paired ions scoring algorithm based on Morpheus for simultaneous identification and quantification of proteome samples prepared by isobaric peptide termini labeling strategies

The isobaric peptide termini labeling (IPTL) method is a promising strategy in quantitative proteomics for its high accuracy, while the increased complexity of MS2 spectra originated from the paired b, y ions has adverse effect on the identification and the coverage of quantification. Here, a paired ions scoring algorithm (PISA) based on Morpheus, a database searching algorithm specifically designed for high‐resolution MS2 spectra, was proposed to address this issue. PISA was first tested on two 1:1 mixed IPTL datasets, and increases in peptide to spectrum matchings, distinct peptides and protein groups compared to Morpheus itself and MASCOT were shown. Furthermore, the quantification is simultaneously performed and 100% quantification coverage is achieved by PISA since each of the identified peptide to spectrum matchings has several pairs of fragment ions which could be used for quantification. Then the PISA was applied to the relative quantification of human hepatocellular carcinoma cell lines with high and low metastatic potentials prepared by an IPTL strategy.

Quantitative secretomic analysis of pancreatic cancer cells in serum-containing conditioned medium

Pancreatic cancer is a highly metastatic and chemo-resistant disease. Secreted proteins involved in cell-cell interactions play an important role in changing the tumor microenvironment. Previous studies generally focus on the secretome of cancer cell line from serum-free media, due to the serious interference of fetal bovine serum (FBS). However, serum-starvation may alter expression patterns of secreted proteins. Hence, efforts to decrease the interference of serum in proteomic analysis of serum-containing media have been hampered to quantitatively measure the tumor secretion levels. Recently, the metabolic labeling, protein equalization, protein fractionation and filter-aided sample preparation (FASP) strategy (MLEFF) has been successfully used to avoid the disturbance of serum on secretome analysis. Here, this efficient method was applied for comparative secretome analysis of two hamster pancreatic cancer cells with differentially metastatic potentials, enabling the observation of 161 differentially expressed proteins, including 106 proteins that had been previously reported and detected in plasma. By integrated analysis of our data and publicly available bioinformatics resources, we found that a combination panel consisting of CDH3, PLAU, and LFNG might improve the prognosis of overall pancreatic cancer survival. These secreted proteins may serve as a potential therapeutic targets for pancreatic cancer metastasis.

Teicoplanin bonded sub-2 μm superficially porous particles for enantioseparation of native amino acids.

Superficially porous particles (SPPs) demonstrate superior efficiency than totally porous particles in chiral separations. In order to obtain high efficiency and fast separation, sub-2 μm SPPs with high surface area are synthesized, and with teicoplanin bonded, such materials are successfully applied into the rapid enantioseparation of native amino acids. In brief, 1.27 ± 0.06 μm nonporous silica particles are prepared by a modified seeded growth method, followed by mesoporous shell fabrication via one-pot templated dissolution and redeposition strategy, and pore size expansion via acid-refluxing. The diameter of the formed SPPs is 1.49 ± 0.04 μm, with the shell thickness as 206 nm. Nitrogen physisorption experiments show that the Brunauer-Emmett-Teller (BET) specific surface area is 213.6 m(2)/g and pore size is 9 nm. After teicoplanin derivatization with bonding capacity as 83.3 μmol/g, the prepared chiral stationary phase is packed into a stainless steel tube with the geometry of 50 mm × 2.1 mm i.d.. In less than 6.4 min, six native amino acids (norleucine, alanine, valine, methionine, leucine, norvaline) are enantioseparated with resolution factors ranging from 1.9 to 5.0. Besides, the resolution for chiral separation is improved with ethanol-water instead of methanol-water as the mobile phase. Moreover, the low temperature gives higher resolution, but longer retention time and higher backpressure. Finally, the effect of flow rate on enantiomeric separation is studied and fast chiral separation within 1 min is obtained with flow rate of 0.4 mL/min. All these results show that the synthesized teicoplanin bonded sub-2 μm SPPs have great potential to achieve the enantioseparation of native amino acids with high resolution and rapid speed.

In-Depth Proteome Coverage by Improving Efficiency for Membrane Proteome Analysis

Although great achievement has been made in the mapping of human proteome, the efficiency of sample preparation still needs to be improved, especially for membrane proteins. Herein, we presented a novel method to deepen proteome coverage by the sequential extraction of proteins using urea and 1-dodecyl-3- methylimidazolium chloride (C12Im-Cl). With such a strategy, the commonly lost hydrophobic proteins by 8 M urea extraction could be further recovered by C12Im-Cl, as well as the suppression effect of high abundance soluble proteins could be decreased. Followed by the in situ sample preparation and separation with different stationary phases, more than 9810 gene products could be identified, covering 8 orders of magnitude in abundance, which was, to the best of our knowledge, the largest data set of HeLa cell proteome. Compared with previous work, not only the number of proteins identified was obviously increased, but also the analysis time was shortened to a few days. Therefore, we expect that such a strategy has great potential applications to achieve unprecedented coverage for proteome analysis.

Decrease of dynamic range of proteins in human plasma by ampholine immobilized polymer microspheres

A novel protein sample pretreatment method based on ampholine immobilized polymer microsphere (ampholine@PM) was developed for the fractionation of intact proteins prior to protein digestion and peptide analysis to reduce the dynamic range of human plasma proteome. After incubation with our prepared ampholine@PM, the captured plasma proteins were successively desorbed by 2M NaCl, 100mM glycine-hydrochloric acid, and 30% (v/v) acetonitrile with 0.1% (v/v) trifluoroacetic acid. The SDS-PAGE results showed the protein dynamic range in such three fractions was obviously reduced as compared with the native plasma. On-particle digestion was ultimately performed to release all proteins retained on ampholine@PM. Followed by MuPIT analysis, the number of identified proteins in plasma was improved by 75% after ampholine@PM treatment. Furthermore, the spectral count of 9 high abundance proteins was decreased by 37.6-97.2%, and the identified low abundance protein (<100ngmL(-1)) number was increased from 4 to 17. These results demonstrated that the fractionation by ampholine@PM could efficiently decrease the protein dynamic range in abundance, beneficial to achieve the deep coverage identification of human plasma proteome.

Ionic liquid-based method for direct proteome characterization of velvet antler cartilage

The cartilage zone of the velvet antler is richly vascularized, this being a major difference to the classical cartilage, in which there are no blood vessels. Angiogenesis and rapid growth of vasculature in velvet antler cartilage (VAC) make it an ideal model for discovering the novel angiogenic regulatory factors. However, the proteomic analysis of VAC is challenging due to the serious interference of proteoglycans (PGs) and collagens. To achieve a comprehensive proteome characterization of VAC, herein, we developed an ionic liquid-based method using 1-dodecyl-3-methylimidazolium chloride ([C12-mim]Cl) for selective extraction of cellular proteins from VAC. Compared with the previous cetylpyridinium chloride (CPC)-based method, the developed [C12-mim]Cl-based method takes much less processing time, shows facile preparation procedure and good compatibility towards downstream proteomic analysis, leading to the identification of more protein groups (1543 vs 753), membrane proteins (663 vs 279) and transmembrane proteins (217 vs 58).

Fast MS/MS acquisition without dynamic exclusion enables precise and accurate quantification of proteome by MS/MS fragment intensity.

Most currently proteomic studies use data-dependent acquisition with dynamic exclusion to identify and quantify the peptides generated by the digestion of biological sample. Although dynamic exclusion permits more identifications and higher possibility to find low abundant proteins, stochastic and irreproducible precursor ion selection caused by dynamic exclusion limit the quantification capabilities, especially for MS/MS based quantification. This is because a peptide is usually triggered for fragmentation only once due to dynamic exclusion. Therefore the fragment ions used for quantification only reflect the peptide abundances at that given time point. Here, we propose a strategy of fast MS/MS acquisition without dynamic exclusion to enable precise and accurate quantification of proteome by MS/MS fragment intensity. The results showed comparable proteome identification efficiency compared to the traditional data-dependent acquisition with dynamic exclusion, better quantitative accuracy and reproducibility regardless of label-free based quantification or isobaric labeling based quantification. It provides us with new insights to fully explore the potential of modern mass spectrometers. This strategy was applied to the relative quantification of two human disease cell lines, showing great promises for quantitative proteomic applications.