Effect of heat and pH denaturation on the structure and conformation of recombinant human hepatic stimulator substance.
Hepatic stimulator substance (HSS) is a novel liver-specific growth-promoting factor. Although HSS has been successfully crystallized, several properties of this protein have yet to be determined. This study shows that recombinant human HSS (rhHSS) is a dimer with a molecular mass of 31 kDa, the protein is weakly acidic and has an isoelectric point (pI) of 4.50. RhHSS was able to protect hepatoma cells from H2O2-induced apoptosis and to stimulate cell growth. The recombinant protein was thermostable up to 80 degrees C and resistant to changes in pH, as determined by synchronous fluorescence and far-UV circular dichroism (CD). Within the range of pH 4.0-10.0, rhHSS assumed a folded conformation identical to the secondary structure of the original, native protein and a native-like far-UV CD spectrum. Denatured rhHSS could be partly reconstituted with respect to its structure, but not its activity. Thus, rhHSS is a structurally stable protein insensitive to thermal and acid-alkaline denaturation.
Yang
Zhi-cheng
ZC
Department of Cell Biology, Capital Medical University, 10 You An Men Wai Xi Tou Tiao, Beijing, 100069, China.
Yang
Lin
L
Zhang
Ying-xia
YX
Yu
He-fen
HF
An
Wei
W
D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002942:Circular Dichroism; D003460:Crystallization; D019281:Dimerization; D006358:Hot Temperature; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D036341:Intercellular Signaling Peptides and Proteins; D016877:Oxidants / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D011489:Protein Denaturation; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D013329:Structure-Activity Relationship
D036341:Intercellular Signaling Peptides and Proteins; D016877:Oxidants; D010455:Peptides; D011994:Recombinant Proteins; C073456:hepatic stimulator substance; D006861:Hydrogen Peroxide