[Purification and activity assay of recombinant growth hormone-releasing hormone].
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.
Wang
Xiao-hua
XH
Department of Biochemistry, Guangzhou Medical College, Guangzhou 510182, China. xh_wang2631@sina.com
Zhang
Na
N
Zhang
Juan-hui
JH
Deng
Hong-zhu
HZ
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
D011994:Recombinant Proteins; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone