Circular dichroism studies on human chorionic gonadotropin and its subunits

Hilgenfeldt, Ulrich; Merz, Wolfgang E.; Brossmer, Reinhard

doi:10.1016/0014-5793(72)80589-1

Cited by 13 publications

(2 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…and the complexity of the association kinetics of the a and /) subunits indicated conformational changes upon formation of the heterodimer (Ingham et al, 1976). Furthermore, a large increase in /$sheet structure of the a subunit upon association has been detected by CD analysis (Garnier et al, 1974;Hilgenfeldt et al, 1974;Holladay and Puett, 1975;Strickland and Puett, 1983), and this increase can only partially be explained by the formation of the intersubunit /I-sheets. Surface-energy calculations have suggested that the a subunit becomes more structured upon reassociation with its / Y subunit (Wu et al, 1994).…”

mentioning

confidence: 99%

NMR Studies of the Free α Subunit of Human Chorionic Gonadotropin

Beer

Zuylen

Leeflang

et al. 1996

European Journal of Biochemistry

View full text Add to dashboard Cite

Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone that is involved in the maintenance of the corpus luteum in early pregnancy. Glycosylation at Am52 of its a subunit (ahCG) is essential for signal transduction, whereas the N-glycan at Am78 stabilizes the structure of the protein.In this study, an almost complete 'H-NMR and a partial "C-NMR spectral assignment for the amino acids and the N-glycans of ahCG and of an enzymatically deglycosylated form, which had a single GlcNAc residue at each of its two glycosylation sites, has been achieved. The secondary structure of ahCG in solution, which was determined based on NOE data, is partially similar to that of the a subunit in the crystal structure of hCG, but large structural differences are found for amino acid residues 33-58.In the crystal structure of hCG, residues 33-37 and 54-58 of the a subunit are part of an intersubunit seven-stranded b-barrel and residues 41 -47 constitute a 3,,,-helix. In contrast, in free ahCG in solution, amino acids 33-58 are part of a large disordered loop, indicating that in intact hCG interactions with the /I subunit of hCG stabilize the conformation of the 0: subunit. The NMR data of ahCG and its deglycosylated counterpart are very similar, indicating that removal of carbohydrate residues other than GlcNAc-1 does not notably affect the conformation of the protein part. However, numerous 'H-NOES between the GlcNAc-1 residue at Am78 and several amino acid residues show that this GlcNAc residue is tightly packed against the protein, being an integral part of the structure of the IX subunit. 'H-NOES across the glycosidic linkages of the glycan, resonance-line widths, and 'H and I3C chemical shifts of the other monosaccharides suggest that the remainder of the glycans at Asn78, and the glycans at Asn.52 are largely extended in solution.

show abstract

mentioning

confidence: 99%

NMR Studies of the Free α Subunit of Human Chorionic Gonadotropin

Beer

Zuylen

Leeflang

et al. 1996

European Journal of Biochemistry

View full text Add to dashboard Cite

show abstract

“…Far ultraviolet circular dichroic (CD) spectra have been reported for hLH and subunits, but no interpretation was given (14,15). In view of the recent CD studies on LH from other species (16-21) and on related glycoprotein hormones (14,15,(19)(20)(21)(22)(23)(24)(25), it is of interest to compare in a detailed fashion the complete C D spectrum of hLH under various conditions with the spectra of the other glycoprotein hormones. Such studies are important not only for elucidating hormone conformation, but also for clarifying the contributions of aromatic residues and disulfides to the C D spectrum.…”

mentioning

confidence: 99%

Circular Dichroism of Human Pituitary Luteinizing Hormone and Its Glycopeptides

Puett

Nureddin

Holladay

1976

International Journal of Peptide and Protein Research

View full text Add to dashboard Cite

The circular dichroic (CD) spectrum of the glycoprotein hormone, human pituitary luteinizing hormone (hLH), has been determined between 195–320 nm and resolved into gaussian constituents. Below 230 nm the CD spectrum is characterized by a negative extremum at 207 nm with a shoulder at 217 nm. Resolution into gaussian constituents of the 200–230 nm CD spectrum resulted in two resolved negative bands, one at 206 nm and the other at 215 nm. The latter band is assigned to β‐structure which is estimated to be about 25%. The 206 nm resolved band is assigned to the N‐acetylated carbohydrate groups (e.g. N‐acetyl glucosamine, galactosamine, and neuraminic acid). This is based partly on the evidence that the CD spectrum of the hLH glycopeptide fraction (prepared by a pronase digestion of s‐carboxymethylated hLH) exhibited a negative extremum at 207.5 nm, which is close to the resolved 206 nm band in hLH. Above 230 nm the CD spectrum is characterized by a negative extremum at about 275 nm. Most of the ellipticity in this region is attributed to the disulfides in hLH. Both strong acid (0.1 N HCl) and concentrated guanidine hydrochloride (4 M) affect the ellipticity in the vicinity of 275 nm, but only the latter (as well as concentrated urea) has a major effect on the CD spectrum below 230 nm indicating extensive conformational changes. There is, however, some loss of β‐structure in 0.1 N HCl. Thus, it appears that the conformation of the hLH subunits in these subunit‐dissociating agents is rather different. There was no dramatic change in the magnitude of the 207 nm extremum of native hLH between 10–50°C.

show abstract

Molecular Aspects of the Subunit Assembly of Glycoprotein Hormones

Garnier

1978

Structure and Function of the Gonadotropins

View full text Add to dashboard Cite

Circular dichroism studies on human chorionic gonadotropin and its subunits

Cited by 13 publications

References 9 publications

NMR Studies of the Free α Subunit of Human Chorionic Gonadotropin

NMR Studies of the Free α Subunit of Human Chorionic Gonadotropin

Circular Dichroism of Human Pituitary Luteinizing Hormone and Its Glycopeptides

Molecular Aspects of the Subunit Assembly of Glycoprotein Hormones

Contact Info

Product

Resources

About