In order to investigate the feasibility of in vitro screening the antitumor activity of natural compounds by trypsin, porcine trypsin was used to for screening test, which is marked by inhibition of enzyme activity. Four compounds, namely daidzin, genistin, matrine and oxymatrine, were selected as test subjects. The natural antitumor drug camptothecin was used as the control. The inhibitory effect was detected by two experimental methods: direct detection of trypsin activity inhibition and hydrolysis of bovine serum albumin by trypsin. The results showed the inhibitory effects of the four natural compounds on trypsin, and the inhibition rates of the four natural compounds were significantly different. The enzyme activity assay showed that the inhibitory effect of matrine was better than that of oxymatrine, indicating that trypsin had a good screening resolution. The inhibitory effect was significantly increased with the increased ratio of sample to trypsin, suggesting the structure-activity correlation and dose-effect correlation of the screening methods. Altogether, the experimental method of screening antitumor activity of natural compounds by trypsin has good application values. Since porcine trypsin is similar to human trypsin in terms of molecular structure and performance, it is more applicable for screening of antitumor efficacy of natural pharmacodynamic compounds.
Humans ; Trypsin/chemistry* ; Alkaloids/pharmacology*

Proteomics is a powerful subject focusing on large-scale study of protein structures and functions. A complete enzymatic digestion of protein complexes is the key step in modern high-resolution and high-throughput mass spectrometry (MS)-based identification and quantification. To achieve MS analysis, both peptide sample pretreatment and data acquisition are prerequisite in proteomic studies. In this paper, we summarized both the enzymatic proprieties of three common proteolytic enzymes, Trypsin, Lys-C and Glu-C, the optimization of multi-enzyme combination and an advanced sample pretreatment in proteomics research.
Enzymes ; chemistry ; Mass Spectrometry ; Proteins ; chemistry ; Proteomics ; methods ; Trypsin ; chemistry

Proteomics is a fast-growing discipline that aims at systematic identification, quantification of proteins and their post-translational modifications in cells. Mass spectrometry-based shotgun proteomics technology is currently one of the mainstream methods for proteomics research. With this method, proteins need to be digested to peptides by site-specific proteases before they can be detected with mass spectrometry. Therefore, site-specific proteases played key roles in this process and so far, a variety of specific proteases have been developed and used in proteomics study. Particularly, the identification, characterization and development of proteases that cleave at the N-termini of corresponding amino acid residues, which are just mirrors to those of typical C-termini proteases, provide novel tools for proteomics analysis. In this review, we summarized the proprieties of LysargiNase, a most recently identified mirror trypsin, and its applications in proteomics research to promote its more widespread usage.
Mass Spectrometry ; Metalloproteases ; chemistry ; metabolism ; Protein Processing, Post-Translational ; Proteomics ; Trypsin ; chemistry

In proteomic research, to improve protein solubility of membrane proteins and nuclear proteins, buffers containing high concentration of detergent, such as 4% SDS, were widely used. However, high concentration of detergent might severely interfere with the downstream proteomic analysis, including protein quantitation and trypsin digestion. To improve the proteomic compatibility of buffers with high concentration of detergent, we used short gel method to pretreat buffers containing detergent. Protein samples were first separated by a short (2-2.5 mm) SDS-PAGE electrophoresis, and proteins were quantitated by comparing with bovine serum albumin standards via optical density analysis. The gel was then cut and peptides were recovered using in-gel digestion. The quantitative linearity range of this method was 1 to 8 μg. The quantitation was accurate and reproducible. After short gel analysis, recovered peptides generated high mass spectrometry signals. In conclusion, short gel method eliminated the interference of high concentration detergent in the proteomics analysis, and it was suitable for protein samples' pretreatment, and was worth to apply in proteomic research.
Detergents ; chemistry ; Electrophoresis, Polyacrylamide Gel ; methods ; Mass Spectrometry ; Membrane Proteins ; chemistry ; Nuclear Proteins ; chemistry ; Proteins ; chemistry ; Proteomics ; methods ; Trypsin

It is hypothesized that protease inhibitors play an essential role in survival of venomous animals through protecting peptide/protein toxins from degradation by proteases in their prey or predators. However, the biological function of protease inhibitors in scorpion venoms remains unknown. In the present study, a trypsin inhibitor was purified and characterized from the venom of scorpion Mesobuthus eupeus, which enhanced the biological activities of crude venom components in mice when injected in combination with crude venom. This protease inhibitor, named MeKTT-1, belonged to Kunitz-type toxins subfamily. Native MeKTT-1 selectively inhibited trypsin with a Kivalue of 130 nmol·L(-1). Furthermore, MeKTT-1 was shown to be a thermo-stable peptide. In animal behavioral tests, MeKTT-1 prolonged the pain behavior induced by scorpion crude venom, suggesting that protease inhibitors in scorpion venom inhibited proteases and protect the functionally important peptide/protein toxins from degradation, consequently keeping them active longer. In conclusion, this was the first experimental evidence about the natural existence of serine protease inhibitor in the venom of scorpion Mesobuthus eupeus, which preserved the activity of venom components, suggests that scorpions may use protease inhibitors for survival.
Amino Acid Sequence ; Animals ; Base Sequence ; Female ; Kinetics ; Male ; Mice ; Molecular Sequence Data ; Protease Inhibitors ; chemistry ; toxicity ; Scorpion Venoms ; chemistry ; genetics ; toxicity ; Scorpions ; chemistry ; genetics ; Trypsin ; chemistry

Structure of a recombinant chimeric anti-CD20 IgG1 monoclonal antibody was verified by the application of high-performance liquid chromatography-mass spectrometry (HPLC-MS)and N-terminal sequencer. Molecular masses, N-terminal sequences and peptide maps of the antibody treated with different reagents and enzymes were measured. Results indicate that the amino acid sequences of light and heavy chains and 10 disulfide bonds were consistent with theoretical structure. By comparison of molecular masses and peptide maps for the fully glycosylated and deglycosylated samples, the N-linked glycosylation site was identified. The method is simple, rapid, precise, and could be referred to the quality control and structure determination of other IgG1 products.
Amino Acid Sequence ; Antibodies, Monoclonal ; chemistry ; Antigens, CD20 ; immunology ; Chromatography, High Pressure Liquid ; Glycosylation ; Immunoglobulin G ; chemistry ; immunology ; Immunoglobulin Heavy Chains ; chemistry ; Immunoglobulin Light Chains ; chemistry ; Mass Spectrometry ; Molecular Weight ; Peptide Mapping ; Recombinant Proteins ; chemistry ; Trypsin ; chemistry

SKPI (shrimp Kunitz-type protease inhibitor) from Marsupenaeus japonicus is a member of serine protease inhibitors which play an important role in the arthropod immunity. To fully understand its function in the innate immunity of shrimp, the skpi gene was cloned into a modified pPIC9K vector with a 6-His tag and expressed by Pichia pastoris GS115. The secretory SKPI was purified from the medium with high purity by using Ni Sepharose High Performance. This results also indicated that the purified SKPI could inhibit the activity of trypsin specifically.
Animals ; Aprotinin ; biosynthesis ; genetics ; isolation & purification ; Pandalidae ; chemistry ; Pichia ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; Serine Proteinase Inhibitors ; biosynthesis ; genetics ; Trypsin Inhibitors

The study was purposed to investigate the apoptosis of HL-60 cells induced by recombinant common buckwheat trypsin inhibitor (rBTI) and its mechanism. The inhibition rate of rBTI on HL-60 cells was detected by MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide); the morphology of HL-60 nuclei was observed by fluorescence microscopy; the apoptosis cells of HL-60 detected by agarose gel electrophoresis and the changes of apoptosis rate was assayed by flow cytometry (FCM), when the HL-60 cells were treated with different concentration of rBTI for 24 hours. The results showed that the growth of HL-60 cells was inhibited evidently after treatment with rBTI in a dose-dependent manner, but there were minimal effects on normal human peripheral blood mononuclear cells (PBMNCs). The nuclei of HL-60 cells showed the characteristics of apoptosis, the analysis by flow cytometry indicated that the apoptosis rate of HL-60 cells was 52% after treatment with rBTI (100 microg/ml), DNA analyzed by agarose gel electrophoresis showed "ladder" pattern. It is concluded that rBTI obviously inhibits growth of HL-60 and induces its apoptosis which provides a foundation for use of recombinant common buckwheat trypsin inhibitor to cure the acute myeloid leukemia.
Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Fagopyrum ; chemistry ; HL-60 Cells ; Humans ; Recombinant Proteins ; biosynthesis ; genetics ; pharmacology ; Trypsin Inhibitors ; biosynthesis ; genetics ; pharmacology

The aim is to determine the primary structure of a new hirudin and reteplase fusion protein (HV12p-rPA) by LC-ESI-MS/MS spectrometry. The molecular weight of the hirudin and reteplase fusion protein (HV12p-rPA) was measured by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The HV12p-rPA was digested with trypsin and chymotrypsin separately and the peptides in the digest mixtures were identified by LC-ESI-MS/MS. The molecular weight of HV12p-rPA was 41,472 Da, which was in accordance with the theoretical value. The peptide fragments of HV12p-rPA digested with trypsin were identified by LC-ESI-MS/MS spectrometry and the results indicated that the fusion protein contained r-PA. Then, the peptides of HV12p-rPA digested with chymotrypsin were identified by the same method. The results indicated that the fusion protein contained HV12p and the linker-containing peptide, DEGGGSY. MASDF and LDWIRDNMRP were identified as the N-terminal and C-terminal containing peptides in the chymotryptic digest mixture of the fusion protein. All of the Xcorr values exceeded 1.5, some of which were above 3.0, showing that the results were correct and credible and a sequence coverage of 85% was achieved. HPLC/MS analysis coupled with uncompleted digestion indicated that all these peptides were arranged with the correct order as expected. Thus, sequence of the fusion protein was confirmed and it was consistent with our design in upstream construction.
Amino Acid Sequence ; Chromatography, Liquid ; methods ; Chymotrypsin ; chemistry ; Fibrinolytic Agents ; analysis ; chemistry ; Hirudins ; analysis ; chemistry ; Molecular Sequence Data ; Molecular Weight ; Peptide Fragments ; Recombinant Fusion Proteins ; analysis ; chemistry ; Recombinant Proteins ; analysis ; chemistry ; Spectrometry, Mass, Electrospray Ionization ; methods ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; methods ; Tandem Mass Spectrometry ; methods ; Tissue Plasminogen Activator ; analysis ; chemistry ; Trypsin ; chemistry

OBJECTIVETo study the protective effect of soybean protease inhibitor on LPS-induced lung injury in rats.

METHODFifty male SD rats were randomly divided in five groups, 10 rats in each group as sham-operation group, model control group, positive medicine group, and high, moderate SBTI groups. Except the sham-group, other groups were induced by intratracheal instillation of LPS with a dose of 6 mg x kg(-1). All rats were given drug throughout intraperitoneal injection except the model controlled group, the positive medicine group was given PMSF with a dose of 50 mg x kg(-1), the high dose group of SBTI was given SBTI with a dose of 100 mg x kg(-1), a dose of the moderate group is 50 mg x kg(-1). We examined all rats in seven days. Index exam: cell quantity, activity of neutrophilic granulocyte released elastic protease proteins in BALF, histopathological examination and so on.

RESULTSoybean protease inhibitor can level down the level of total protein, cell quantity, PMN percent, activity of neutrophilic granulocyte in BALF. SBTI level down the content of NF-kappa B in nucleoprotein, while increase the content of I kappa B alpha in plasmoprotein.

CONCLUSIONSBTI is useful in protecting experimental pulmonary injury induced by LPS in rats.

Acute Lung Injury ; chemically induced ; drug therapy ; metabolism ; pathology ; Animals ; Endotoxins ; toxicity ; Granulocytes ; drug effects ; metabolism ; pathology ; I-kappa B Proteins ; metabolism ; Male ; NF-KappaB Inhibitor alpha ; Rats ; Soybeans ; chemistry ; Transcription Factor RelA ; metabolism ; Trypsin Inhibitors ; pharmacology