Skip Navigation

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by Sakakibara, R.
Right arrow Articles by Ishiguro, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sakakibara, R.
Right arrow Articles by Ishiguro, M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

J. Biochem, 1990, Vol. 107, No. 6 858-862
© 1990 Japanese Biochemical Society

research-article

A Nicked ß-Subunit of Human Chorionic Gonadotropin Purified from Pregnancy Urine1

Ryuzo Sakakibara, Shuichi Miyazaki and Masatsune Ishiguro

Department of Biochemistry, School of Clinical Pharmaceutical Sciences, Nagasaki University Nagasaki, 852

Human chorionic gonadotropin (hCG) is a glycoprotein hormone composed of two dis-simialr subunits ({alpha} and ß) and normally excreted in urine of pregnant women. An uncommon ß-subunit of hCG was purified from fresh early normal pregnancy urine by Sepralyte C8 resin adsorption, Sephadex G-100 column chromatography, and reverse-phase HPLC. SDS-PAGE under non-reducing conditions showed that the apparent molecular weight (39,000) of this ß-subunit was extremely similar to that of the native ß-subunit, which is known to consist of 145 amino acid residues and carbohydrates. However, SDS-PAGE, under reducing conditions, resulted in two bands with apparent molecular weights of 22,000 and 18,000, indicating that it consisted of two peptide fragments connected with disulfide bridge(s). These two peptide fragments, separated and purified from the reduced and carboxymethylated protein, were subjected to amino acid and N-terminal sequence analyses. It was found that this ß-subunit consisted of two polypeptide chains composed of residues 1-47 disulfide-bridged to residues 48-145 of the ß-subunit, which may be produced by nicking of the ß-subunit at the one site (Gly47-Val48). This ß-subunit was termed a nicked ß-subunit of hCG (N-hCGß). It was also found that N-hCG;9 was present in urine as an a({alpha}ß dimer, indicating that an intrachain nicking of this site in the y9-subunit does not inhibit {alpha}ß dimer formation. However, this nick in the subunit did reduce a hormonal activity (the stimulatory effect on testosterone production in rat Leydig cells) of hCG, since the activity of hCG reconstituted with N-hCG7ß and intact {alpha}-subunit was significantly lower than that of intact hCG.

1 This work was supported by a Grant-in-Aid (63570133) from the Ministry of Education, Science and Culture of Japan.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Clin. Chem.Home page
G. Kovalevskaya, S. Birken, T. Kakuma, J. Schlatterer, and J. F. O'Connor
Evaluation of Nicked Human Chorionic Gonadotropin Content in Clinical Specimens by a Specific Immunometric Assay
Clin. Chem., January 1, 1999; 45(1): 68 - 77.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.