Growth hormone from striped catfish (Pangasianodon hypophthalmus): genomic organization, recombinant expression and biological activity.
Growth hormone is an essential polypeptide required for normal growth and development of vertebrates. In this report, striped catfish (Pangasianodon hypophthalmus) growth hormone gene and cDNA were isolated by reverse transcriptase-polymerase chain reaction. The striped catfish growth hormone (scGH) encoding gene contains 5 exons and 4 introns. The cDNA sequence of the scGH gene contains a 603bp open reading frame and encodes for a 200-aa protein consisting of a putative 22-aa signal peptide and the mature 178-aa protein. The recombinant histidine-tagged scGH protein which expressed in Escherichia coli as inclusion bodies was unfolded, refolded and purified to near-homogeneity by Ni(2+)-NTA chromatography. Analysis of the secondary structure content by CD spectroscopy showed that the α-helical content of the refolded scGH is 55%. Elucidation of the folding pathway of scGH by fluorescence spectroscopy showed that denaturation transition of scGH is coincident and cooperative, consistent with the two-state denaturation mechanism. The purified scGH was biologically active and exhibited growth-promoting activity in striped catfish, but not tilapia.
Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, 10900 Thailand.
Sinothai
S
Poen
Somchai
S
Pornbanlualap
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002397:Catfishes / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013006:Growth Hormone / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017210:Tilapia / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D029941:Fish Proteins; D013006:Growth Hormone