1
|
Amoresano A, Orrù S, Siciliano RA, De Luca E, Napoleoni R, Sirna A, Pucci P. Assignment of the complete disulphide bridge pattern in the human recombinant follitropin beta-chain. Biol Chem 2001; 382:961-8. [PMID: 11501762 DOI: 10.1515/bc.2001.120] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The chemical assessment of the complete disulphide bridge pattern in the beta-chain of human recombinant follicotropin (betaFSH) was accomplished by integrating classical biochemical methodologies with mass spectrometric procedures. A proteolytic strategy consisting of a double digestion of native betaFSH using the broad-specificity protease subtilisin first, followed by trypsin, was employed. The resulting peptide mixture was directly analysed by FAB-MS, leading to the assignment of the first three disulphide bridges. The remaining S-S bridges were determined by HPLC fractionation of the proteolytic digest followed by ESMS analysis of the individual fractions. The pattern of cysteine couplings in betaFSH was determined as: Cys3-Cys5l, Cys17-Cys66, Cys20-Cys104, Cys28-Cys82, Cys32-Cys84 and Cys87-Cys94, confirming the arrangement inferred from the crystal structure of the homologous betaCG. A subset of the S-S bridge pattern comprising Cys3-Cys51, Cys28-Cys82 and Cys32-Cys84 constitutes a cysteine knot motif similar to that found in the growth factor superfamily.
Collapse
Affiliation(s)
- A Amoresano
- Centro Internazionale di Servizi di Spettrometria di Massa, CNR-Università di Napoli Federico II, Napoli, Italy
| | | | | | | | | | | | | |
Collapse
|
2
|
Fairlie WD, Stanton PG, Hearn MT. The disulphide bond structure of thyroid-stimulating hormone beta-subunit. Biochem J 1996; 314 ( Pt 2):449-55. [PMID: 8670056 PMCID: PMC1217071 DOI: 10.1042/bj3140449] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Previously only one of the six disulphide bonds within the beta-subunit of bovine thyrotropin (bTSH beta) has been unequivocally assigned. In the present investigation, the fluorescent alkylating reagent 5-N-[(iodoacetamidoethyl)amino]naphthalene-1-sulphonic acid has been employed as part of a double-alkylation strategy to allow the relative reactivities and the location of the six disulphide bonds of bTSH beta, after selective reduction, to be assigned by using reversed-phase HPLC peptide mapping techniques and associated methods of structural analysis. The most reactive disulphide bond was Cys88-Cys95; the second most reactive group of disulphide bonds involved the half-cystine residues Cys16, Cys19, Cys67 and Cys105 with the experimental results consistent with the assignment of disulphide bonds to Cys16-Cys67 and Cys19-Cys105. The least reactive group of half-cystine residues consisted of Cys2, Cys27, Cys31, Cys52, Cys83 and Cys85. The isolation, by high-performance ion-exchange chromatography, of a partly reduced bTSH beta derivative in which only the half-cystine residues Cys31, Cys85, Cys88 and Cys95 were labelled enabled the assignment of a previously uncharacterized disulphide bond to Cys31-Cys85. The remaining two assignments, Cys2-Cys52 and Cys27-Cys83, were made by comparison with the recently published human chorionic gonadotropin crystal structure. The flexibility of the double-labelling approach used in these studies demonstrates that only very small quantities are required for proteins containing an extensive number of half-cystine residues such as TSH beta, owing to the combination of the high resolution of the reversed-phase HPLC peptide mapping procedures and the sensitivity of the fluorimetric detection method.
Collapse
Affiliation(s)
- W D Fairlie
- Centre for Bioprocess Technology, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | | | | |
Collapse
|
3
|
Wako H, Ishii S. Secondary structure prediction of beta-subunits of the gonadotropin-thyrotropin family from its aligned sequences using environment-dependent amino-acid substitution tables and conformational propensities. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1247:104-12. [PMID: 7873578 DOI: 10.1016/0167-4838(94)00216-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The secondary structures of beta-subunits of the glycoprotein hormone family, LH (luteinizing hormone), CG (chorionic gonadotropin), FSH (follicle stimulating hormone), TSH (thyroid stimulating hormone), and GTH I/GTH II (two types of fish gonadotropins), are predicted by comparing an amino-acid substitution pattern at equivalent sites in their aligned sequences with environment-dependent amino-acid substitution tables and conformational propensities calculated from other protein families whose three-dimensional structures are known. According to the prediction results, together with other structural information obtained from experiments, the following points come up as important structural features of the beta-subunits of this family; The regions assigned to regular secondary structures (one alpha-helix and three beta-strands) are considered to constitute a core of the beta-subunits. They involve interaction sites with carbohydrate and alpha-subunit. Out of the six disulfide bonds formed in the beta-subunit, four are located together on one side of the core, and the other two on the opposite side. The two regions assumed to be a receptor binding region from experiments (therefore, species-specific regions) are predicted as loops located on the same side of the beta-subunit in this study. Some of the predicted loops are rich in proline residues. While the positions of proline residues are conserved in the family generally, there are hormone- or species-specific ones in the loop that is assumed to take part in receptor binding. The possible importance of proline residues in hormone or species specificity is discussed. (After submitting the manuscript the X-ray crystal structure of human CG was published. In order to evaluate the prediction, the original manuscript is kept intact and a comparison has been made between the prediction results and the crystal structure in an appendix).
Collapse
Affiliation(s)
- H Wako
- School of Social Sciences, Waseda University, Tokyo, Japan
| | | |
Collapse
|
4
|
Huang J, Ujihara M, Xia H, Chen F, Yoshida H, Puett D. Mutagenesis of the 'determinant loop' region of human choriogonadotropin beta. Mol Cell Endocrinol 1993; 90:211-8. [PMID: 7684341 DOI: 10.1016/0303-7207(93)90154-c] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The hormone-specific beta subunits of the four human glycoprotein hormones are homologous, and mapping studies are underway in many laboratories to delineate the amino acid residues responsible for receptor binding and activation. Results on the human choriogonadotropin beta (hCG beta) subunit, obtained using synthetic peptides, chemically modified derivatives, and mutant forms prepared via site-directed mutagenesis, have suggested that amino acid residues enclosed by the purported disulfide loop between Cys-93 and Cys-100 may contribute to receptor binding and perhaps specificity. Indeed, the 93-100 amino acid sequence is referred to as a determinant loop. We have used site-directed mutagenesis to prepare single amino acid residue replacements at positions not previously investigated in full length beta subunits; these include Arg-95, Ser-96, Thr-97, and Thr-98. In addition, Leu-92 was studied in an effort to determine whether changes immediately adjacent to the determinant loop alter receptor binding. The wild-type and mutant cDNAs for hCG beta were subcloned into a Prsv expression vector and transiently transfected into Chinese hamster ovary cells containing a stably integrated gene for bovine alpha. The concentrations of total expressed hCG beta in heterodimer form with the bovine alpha subunit were determined by radioimmunoassays. The mutant gonadotropins were assayed in vitro using a competitive binding assay with [125I]hCG and progesterone production, both in the transformed murine Leydig cell line, MA-10. Mutant beta subunits containing the replacements Lys-92, Ser-95, Asp-96, and Tyr-97 exhibited normal alpha subunit binding.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- J Huang
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, FL 33101
| | | | | | | | | | | |
Collapse
|
5
|
Stockell Hartree A, Renwick AG. Molecular structures of glycoprotein hormones and functions of their carbohydrate components. Biochem J 1992; 287 ( Pt 3):665-79. [PMID: 1445230 PMCID: PMC1133060 DOI: 10.1042/bj2870665] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- A Stockell Hartree
- AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, U.K
| | | |
Collapse
|
6
|
Zhou ZR, Smith DL. Assignment of disulfide bonds in proteins by partial acid hydrolysis and mass spectrometry. JOURNAL OF PROTEIN CHEMISTRY 1990; 9:523-32. [PMID: 2085377 DOI: 10.1007/bf01025005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A new method is described for locating disulfide bonds in proteins which cannot be cleaved between half-cystinyl residues by enzymic methods, as is often the case for tightly coiled proteins, or for proteins in which half-cystinyl residues are not separated by residues required for enzymic cleavage. Partial acid hydrolysis of a model protein, hen egg-white lysozyme, produces a mixture of disulfide-containing peptides from which the disulfide connections may be deduced. The usefulness of a combination of HPLC, fast atom bombardment mass spectrometry, and computer-assisted analysis to identify disulfide-containing peptides present in the partial acid hydrolysate of the model protein is demonstrated. Chromatographic fractions of the hydrolysate were analyzed by mass spectrometry before and after chemical reduction of the disulfide bonds to determine the molecular weights of disulfide-containing peptides. Computer-assisted analysis was then used to relate the molecular weights of these peptides to specific segments of the protein from which the disulfide connectivities could be determined. Partial acid hydrolysis of proteins, which is attractive because it proceeds relatively independent of the amino acid sequence and structure, and because disulfide interchange is unlikely to occur in dilute acid, has become practical because disulfide-containing peptides present in complex mixtures can be identified rapidly and definitively by this method.
Collapse
Affiliation(s)
- Z R Zhou
- Department of Medicinal Chemistry and Pharmacognosy, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, Indiana 47907
| | | |
Collapse
|
7
|
Suganuma N, Matzuk MM, Boime I. Elimination of disulfide bonds affects assembly and secretion of the human chorionic gonadotropin β subunit. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47301-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
8
|
Rathnam P, Tolvo A, Saxena BB. Elucidation of the disulfide bond positions of the beta-subunit of human follicle-stimulating hormone. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 708:160-6. [PMID: 6816284 DOI: 10.1016/0167-4838(82)90216-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
9
|
Reeve JR, Pierce JG. Disulfide bonds of glycoprotein hormones. Their selective reduction in the beta subunits of bovine lutropin and thyrotropin. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1981; 18:79-87. [PMID: 7309370 DOI: 10.1111/j.1399-3011.1981.tb02042.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
10
|
Mise T, Bahl O. Assignment of disulfide bonds in the beta subunit of human chorionic gonadotropin. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69030-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
11
|
|
12
|
Fujiki Y, Rathnam P, Saxena BB. Studies on the disulfide bonds in human pituitary follicle-stimulating hormone. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 624:428-35. [PMID: 6774759 DOI: 10.1016/0005-2795(80)90084-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Human follicle-stimulating hormone (FSH) was digested with subtilisin, thermolysin, cyanogen gromide, pronase and trypsin to isolate the cystine-containing peptides. These peptides were purified by gel filtration through Sephadex G-50 column and by high-voltage paper electrophoresis at pH 6, 3.5 and/or 2. The location of the cystine-containing peptides in human FSH alpha- and beta-subunits was established by amino acid composition, end-group analysis and determination of the amino acid sequence by Edman degradation. The results indicate that the disulfide bonds are present between half-cystine residues located between positions 7 and 10, 28 and 87 and 82 and 84 in the alpha-subunit, and between positions 3 and 28, 17 and 51 and 32 and 104 in the beta-subunit of human FSH.
Collapse
|
13
|
Weare JA, Reichert LE. Studies with carbodiimide-cross-linked derivatives of bovine lutropin. II. Location of the cross-link and implication for interaction with the receptors in testes. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50270-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
14
|
Tsunasawa S, Liu WK, Burleigh BD, Ward DN. Studies of disulfide bond location in ovine lutropin beta subunit. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 492:340-56. [PMID: 884134 DOI: 10.1016/0005-2795(77)90085-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
By combinations of selective chemical cleavage (cyanogen bromide), selective enzymatic cleavage (trypsin, thermolysin), and random cleavage (partial acid hydrolysis) a series of disulfide-containing peptides have been isolated from ovine lutropin beta subunit. These peptides suggest six disulfide linkages between half-cystine residues in positions 23-72, 26-110, 93-100, 34-88, 9-90, and 38-57. The latter pair was placed by elimination of other possibilities. The first three pairs are in agreement with a report by Chung, D., Sairam, M. R. and Li, C. H. (1975) Int. J. Peptide Protein Res. 7, 487-493; the pair 93-100 has also been detected by Reeve, J. R., Cheng, K. W. and Pierce, J. G. (1975) Biochem. Biophys. Res. Commun. 67, 149-155, using partial reduction and alkylation. In an attempt to improve the efficiency of enzymatic attack, a preliminary partial reduction as per Reeve et al. [16] was done. In this instance a peptide suggesting an additional disulfide linkage between half-cystines 23-26 was obtained as well as peptides consistent with the 23-72 and 26-110 placements. This was interpreted as an artifactual opening and recombining during partial reduction-reoxidation to produce the 23-26 linkage. The placement of three disulfide bonds (34-88, 9-90, and 38-57) is in disagreement with the pairings Chung et al. [15] suggest for these six half-cystine residues. Six reasons for uncertainty in the placement of disulfide bonds are discussed. It is concluded the definitive placement of the disputed three disulfide bonds in ovine lutropin beta subunit remains an open question.
Collapse
|
15
|
Mori KF, Hum VG, Botting HG. Partial reduction with dithiothreitol of disulfide bonds in human chorionic gonadotropin. Mol Cell Endocrinol 1977; 6:181-90. [PMID: 832762 DOI: 10.1016/0303-7207(77)90084-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Of the eleven disulfide bonds of human chorionic gonadotropin (hCG), two were reduced with a 10-fold molar excess of dithiothreitol (DTT) relative to hormone. An S-carboxymethyl (SCM) derivative and a reoxidized product of this reduced hCG retained full biologic activity and were likely to be immunologically identical with native hCG. These two disulfide bonds appeared to be located in the alpha-subunit of the hormone. A 40-fold molar excess of DTT was required to reduce the third disulfide bond which was located in the beta-subunit. An SCM derivative ot this hexa-SH-hCG was only one fifth as biologically active as native hCG but its immunologic activity was only slightly decreased. However, its reoxidized product exhibited over 70% of the biologic activity of and it had nearly the same immunologic activity as the hormone. Reduction of a fourth disulfide bond, probably in the beta-subunit, by a 100-fold molar excess of the reagent was accompanied by considerable alterations in the hormone conformation as evidenced by electrophoresis. The resulting SCM derivatives as well as reoxidized products showed progressive decreases in biologic and immunologic activity and both reduced deca-SCM-hCG and a reoxidized product of deca-SH-hCG were virtually devoid of biologic activity. These findings suggest that the two first-reduced disulfide bonds, apparently in the alpha-subunit, are not important to the biologic activity of the hormone and that the third-reduced disulfide bond, probably in the beta-subunit, is very important in maintaining a biologically active conformation of the hormone. Further disulfide reduction appears to result in considerable alterations in the general conformation of the hormone, including disulfide interchange.
Collapse
|
16
|
Pierce JG, Giudice LC, Reeve JR. Studies on the disulfide bonds of glycoprotein hormones. Course of reduction of bovine luteinizing hormone, bovine thyroid-stimulating hormone, and their subunits. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(20)81873-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|