title: Immunological characterization and verification of recombinant streptococcal protein G.
abstract: Streptococcal protein G (SPG), which is an antigen of the Streptococcus sp. cell wall, is important due to its high specificity to immunoglobulin (Ig), as compared with staphylococcal protein A. However, the cost of commercial recombinant (r)SPG has so far hindered further research into the application of rSPG. Efficient high cell density fermentation of genetically modified Escherichia coli and purification technology have previously been studied as a means to obtain rSPG. In the present study, the immunological characterization of purified rSPG was compared with commercial SPG via western blot analysis. The results of the present study demonstrated that the IgG‑binding capacity of purified rSPG was markedly higher, as compared with commercial SPG. Furthermore, purified rSPG cross‑linked with Q Sepharose® Fast Flow exhibited excellent affinity with IgG in murine serum. In order to obtain relatively pure and accurate rSPG, the purified rSPG was identified by Nanoflow Liquid Chromatography‑Mass Spectrometry (MS)/MS spectrum. The results indicated that the two peptide fragments of purified rSPG corresponded to the Streptococcus sp. GX7805 protein G as listed in the National Center for Biotechnology Information database. The method described in the present study offers a novel practical method for the verification of rSPG in relatively pure form, in order to purify IgG or carry out immunolabeling processes.
authors.affiliation: Department of Biological Engineering, Beijing Polytechnics, Beijing 100176, P.R. China.
authors.forename: Hucheng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Beijing Buchang Pharm Biopharmaceutical R&D Center, Beijing 100080, P.R. China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Liang
authors.affiliation: Department of Biological Engineering, Beijing Polytechnics, Beijing 100176, P.R. China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Fan
authors.affiliation: Department of Biological Engineering, Beijing Polytechnics, Beijing 100176, P.R. China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Biological Engineering, Beijing Polytechnics, Beijing 100176, P.R. China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Yang
authors.affiliation: Department of Biological Engineering, Beijing Polytechnics, Beijing 100176, P.R. China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Biological Engineering, Beijing Polytechnics, Beijing 100176, P.R. China.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Life Sciences, Tianjin Normal University, Tianjin 300384, P.R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Liang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification*; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007074:Immunoglobulin G / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification; D013205:Staphylococcal Protein A; D013291:Streptococcus / Q000235:genetics* / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D013205:Staphylococcal Protein A