title: [Purification and activity assay of recombinant growth hormone-releasing hormone].
abstract: OBJECTIVE
  To express recombinant growth hormone-releasing hormone (GHRH) peptide in E.coli by genetic engineering and examine its biological activity.
  
  
  METHODS
  GHRH peptide was purified to homogeneity by means of cell lysis, washing, ethanol precipitation, acid hydrolysis, SP-Sephadex C25 and Sephadex G-25 column chromatographies.
  
  
  RESULTS
  SDS-PAGE showed that the recombinant plasmid pET-28a /L-ansB-GHRH in E.coli BL21(DE3) expressed the fusion protein under the induction with IPTG. The fusion protein was expressed in the form of inclusion body, accounting for 30% of the total bacterial protein. After the purification procedures, the peptide was purified about 147-fold with a peptide yield of 0.68%. The molecular mass of the peptide was 5 235 Da as determined by electrospray ionization (ESI) mass spectrum, in agreement with the predicted value, and SDS-PAGE presented a single peak in assessment of the purity. Experiment showed that there were significant differences in the growth hormone released by the peptide between the dose groups and the blank control group, and the differences tended to be more obvious with the increase of the doses.
  
  
  CONCLUSIONS
  The recombinant GHRH peptide possesses good biological activities.
authors.affiliation: Department of Biochemistry, Guangzhou Medical College, Guangzhou 510182, China. xh_wang2631@sina.com
authors.forename: Xiao-hua
authors.initials: XH
authors.lastname: Wang
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
authors.forename: Juan-hui
authors.initials: JH
authors.lastname: Zhang
authors.forename: Hong-zhu
authors.initials: HZ
authors.lastname: Deng
mesh_terms: D000818:Animals; D013006:Growth Hormone / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000302:isolation & purification* / Q000494:pharmacology; D008970:Molecular Weight; D051381:Rats; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone