An important index determination for clinical diagnosis of renal function is to assay the creatinine concentration in serum. In the analytical process applied with coupled-enzyme, the quality control of sarcosine oxidase (SOX) as a key enzyme is the first problem to be solved. In order to establish an efficient and laboratory-scale production of SOX, the recombinant sarcosine oxidase (r-SOX) gene was a high-level expression in E. coli induced with lactose on a large-scale fermentation in 300 L fermenter. The results suggested that the biomass concentration reached OD600 of 22 and the expression of recombinant sarcosine oxidase in E. coli accounted for about 25% of total soluble protein in culture after fermentation. The cell-free extract obtained from high pressure homogenizer was processed by selective thermal denaturation and then purified with Ni-Sepharose FF chromatography. The sarcosine oxidase with 97% purity, 25 U/mg specific activity and 92.4% activity recovery was obtained. The molecular weight with single peptide chain of 53 kD and 55 kD of recombinant sarcosine oxidase was assessed by SDS-PAGE in presence or absence of 2-mercaptoehanol and Sephacryl S-200 chromatography. This sarcosine oxidase was found to be a conjugated protein, yellow enzyme, which combined with FAD as prosthetic group by covalent linkage. The contaminant of catalase was not detected in the sample pool of this enzyme. In addition, a further test to the thermal stability of sarcosine oxidase was done. According to the above results, the development and utilization of this enzyme has been set up on a reliable foundation.
Escherichia coli ; Fermentation ; Recombinant Proteins ; biosynthesis ; Sarcosine Oxidase ; biosynthesis

Recombinant collagen, as an alternative to natural collagen, has the potential to be widely used in biomaterials, biomedicine, etc. Diverse recombinant collagens and their variants can be industrially produced in a variety of expression systems, which lays a foundation for exploring and expanding the clinical application of recombinant collagens. We reviewed different expression systems for recombinant collagens, such as prokaryotic expression systems, yeast expression systems, as well as plant, insect, mammal, and human cell expression systems, and introduced the advantages, potential applications, and limitations of recombinant collagen. In particularly, we focused on the current progress in the recombinant collagen production, including recombinant expression system construction and hydroxylation strategies of recombinant collagen, and summarized the current biomedical applications of recombinant collagen.
Animals ; Biocompatible Materials ; Collagen/biosynthesis* ; Humans ; Hydroxylation ; Recombinant Proteins/biosynthesis*

Limulus Factor C, a serine protease zymogen from the amoebocytes of the limulus, has high affinity for endotoxin. When Factor C is activated by endotoxin, it hydrolyses artificial tripeptide substrate and measurable products are released, so it can be used as an alternative reagent for endotoxin analysis. Factor C gene of Tachypleus tridentatus was obtained through RT-PCR and the recombinant protein was expressed by Bac-to-Bac/BmNPV baculovirus expression system in silkworm larvae. The activity of Factor C was detected with diluted serum of silkworm larvae, and the sensitivity of endotoxin detected was 0.2 EU/mL when the serum was diluted at 1:500. The silkworm larvae expressed limulus Factor C could be used to develop a new low-cost endotoxin test reagent.
Animals ; Arthropod Proteins ; biosynthesis ; Baculoviridae ; Bombyx ; metabolism ; Enzyme Precursors ; biosynthesis ; Genetic Vectors ; Larva ; metabolism ; Recombinant Proteins ; biosynthesis ; Serine Endopeptidases ; biosynthesis

To seek the reason of heterogeneity of recombinant HWTX-I (rHWTX-I) expressed in Pichia pastoris. We expressed HWTX-I gene of interest in Pichia pastoris GS115/HWTX-I. The heterogenous product expressed was separated, purified and identified by using Ion exchange HPLC, reverse HPLC, Tricine SDS-PAGE and MALDI-TOF Mass Spectrometry and then sequenced in both N-terminus and C-terminus. These results show that the heterogeneity of rHWTX-I results from the incomplete processing of signal peptide of N-terminus and the internal degradation of C-terminus. Biological activity assay shows that the activity of the heterogenous rHWTX-I only showed 30% activity compared with the native HWTX-I. The Solutions to how to avoid the heterogeneity are also discussed.
Animals ; Neurotoxins ; biosynthesis ; genetics ; Pichia ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; Reptilian Proteins ; biosynthesis ; genetics ; Spider Venoms ; biosynthesis ; genetics

Yarrowia lipolytica lipase Lip2 (YlLip2) is an important industrial enzyme with many potential applications. To alleviate the dissolved oxygen (DO) limitation and improve YlLip2 production during high-cell density fermentation, the YlLip2 gene lip2 and Vitreoscilla hemoglobin (VHb) gene vgb were co-expressed in Pichiapastoris under the control of AOX1 and PsADH2 promoter, respectively. The PsADH2 promoter from Pichia stipitis could be activated under oxygen limitation. The SDS-PAGE and CO-difference spectrum analysis indicated that VHb and YlLip2 had successfully co-expressed in recombinant strains. Compared with the control cells (VHb-, GS115/9Klip2), the expression levels of YlLip2 in VHb-expressing cells (VHb+, GS115/9Klip2-pZPVT) under oxygen limitation were improved 25% in shake-flask culture and 83% in a 10 L fermentor. Moreover, the VHb+ cells displayed higher biomass than VHb- cells at lower DO levels in a 10 L fermentor. In this study, we also achieved a VHb-expressing clone harboring multicopy lip2 gene (GS115/9Klip2-pZPVTlip2 49#), which showed the maximum lipolytic activity of 33 900 U/mL in a 10 L fermentor under lower DO conditions. Therefore, it can be seen that expression of VHb with PsADH2 promoter in P. pastoris combined with increasing copies of lip2 gene is an effective strategy to improve YlLip2 production.
Bacterial Proteins ; biosynthesis ; genetics ; Fermentation ; Fungal Proteins ; biosynthesis ; genetics ; Lipase ; biosynthesis ; genetics ; Oxygen ; analysis ; pharmacology ; Pichia ; metabolism ; Protein Engineering ; Recombinant Proteins ; biosynthesis ; genetics ; Truncated Hemoglobins ; biosynthesis ; genetics

OBJECTIVETo express the L1 protein of human papillomavirus type 16 (HPV16) in insect cell suspension culture system.

METHODSOptimized the conditions of suspension culture, recombinant virus amplification and protein expression. Determined the virus tilter by plague analysis and detected the target protein by SDS-PAGE and Western blot; The formation of VLPs by HPV16 L1 protein was observed with TEM.

RESULTSThe Sf9 cells could grow better in suspension culture with seeding density of 5 x 10-5 cell/mL and the maximum expression quantity was obtained by infection of cells with rBacV/HPV16L1 (MOI =10) and harvesting after 72-84 h. HPV16L1 protein could assemble into VLPs in Sf9 cells observed with TEM.

CONCLUSIONThe conditions of cell culture, virus amplification and protein expression were optimized. HPV16 L1 protein could assemble into VLPs in Sf9 cells, which would provide a foundation for further study of the vaccine and diagnosis kits.

Animals ; Capsid Proteins ; biosynthesis ; Cell Proliferation ; Oncogene Proteins, Viral ; biosynthesis ; Recombinant Proteins ; biosynthesis ; Spodoptera ; Suspensions ; Virion ; ultrastructure

To construct and express a composite gene vaccine for human papillomavirus 58(HPV58)-associated cervical cancer, we inserted HPV58mE6E7 fusion gene into pCI-Fc-GPI eukaryotic expression vector, constructing a recombinant plasmid named pCI-sig-HPV58mE6E7-Fc-GPI. Then we further inserted fragment of sig-HPV58mE6E7Fc-GPI into the novel vaccine vector PVAX1-IRES-GM/B7, constructing PVAX1-HPV58mE6E7FcGB composite gene vaccine. PVAX1-HPV58mE6E7FcGB vaccine was successfully constructed and identified by restriction endonuclease and sequencing analysis. Eukaryotic expression of fusion antigen sig-HPV58mE6E7-Fc-GPI and molecular ad-juvant GM-CSF and B7. 1 were proved to be realized at the same time by flow cytometry and immunofluorescence. So PVAX1-HPV58mE6E7FcGB can be taken as a candidate of therapeutic vaccine for HPV58-associated tumors and their precancerous transformations.
Cancer Vaccines ; biosynthesis ; genetics ; Capsid Proteins ; biosynthesis ; genetics ; Female ; Humans ; Oncogene Proteins, Viral ; biosynthesis ; genetics ; Papillomavirus E7 Proteins ; biosynthesis ; genetics ; Papillomavirus Vaccines ; biosynthesis ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Uterine Cervical Neoplasms ; prevention & control ; Vaccines, DNA ; biosynthesis

We cloned genes of four sentrin-specific protease (SENP), three small ubiquitin-like modifiers (SUMO), enhanced cyan fluorescent protein (ECFP) and yellow fluorescent protein (EYFP) by two-step PCR. Then we constructed expression vector B28 for SENP and B13 for ECFP-SUMO-EYFP. The recombinant plasmids were transformed into Escherichia coli BL21 and expression was induced by isopropyl beta-D-thiogalactoside, then recombinant proteins were purified by Ni-NTA agarose column ion-exchange chromatography. The proteins were analyzed with SDS-PAGE and identified with Western blotting. Except that SENP3 catalytic domain (SENP3C) truncated in the C termini and SENP5C expressed in inclusion body, others were expressed as soluble proteins. SDS-PAGE analysis showed that the relative molecular mass of these fusion proteins were consistent with theoretical ones, and the specificity of the fusion proteins were confirmed with Western blotting. The fusion proteins of SENP and ECFP-SUMO-EYFP can be successfully expressed in prokaryotic expression system. It lays the foundation for the fluorescence resonance energy transfer analysis.
Bacterial Proteins ; biosynthesis ; genetics ; Catalytic Domain ; Cysteine Endopeptidases ; biosynthesis ; genetics ; Endopeptidases ; biosynthesis ; genetics ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Green Fluorescent Proteins ; biosynthesis ; genetics ; Humans ; Luminescent Proteins ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; SUMO-1 Protein ; biosynthesis ; genetics

Hemoglobinuria, Paroxysmal ; metabolism ; Humans ; Membrane Proteins ; biosynthesis

The coding sequence for the mature peptide of porcine lactoferrin (Plf) was synthesized according to the codon usage of lactobacillus, to establish optimized porcine lactoferrin Lactobacillus expression system. The gene was ligated into the Xho I/BamH I site of Lactobacillus expression vector pPG612.1 and the recombinant plasmid pPG612.1-plf was transformed individually into Lactobacillus casei ATCC393, Lactobacillus pentosus KLDS1.0413, Lactobacillus plantarum KLDS1.0344 or Lactobacillus paracasei KLDS1.0652 by electroporation. After induction with xylose, expression of the recombinant proteins was detected by Western blotting and confocal laser scanning microscopy. Secretion of recombinant Plf proteins from four recombinant species was determined quantitatively by ELISA. The antibacterial activities of recombinant proteins were measured by agar diffusion method. The result shows that Plf was correctly expressed in four species of recombinant lactobacillus, with molecular weight of about 73 kDa. The expression levels in recombinant Lactobacillus casei, Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus paracasei were 9.6 μg/mL, 10.8 μg/mL, 12.5 μg/mL and 9.9 μg/mL, respectively. Antimicrobial activity experiment shows that the recombinant proteins were active against E. coli, Staphylococcus aureus, Salmonella typhimurium, Listeria, Pasteurella. The recombinant Plf expressed by recombinant Lactobacillus plantarum showed the best antibacterial activity among all recombinant lactobacillus species. These data represent a basis for the development and application of porcine lactoferrin from recombinant lactobacillus.
Animals ; Anti-Bacterial Agents ; biosynthesis ; Lactobacillus ; metabolism ; Lactoferrin ; biosynthesis ; Recombinant Proteins ; biosynthesis ; Swine