The contribution of helical potential to the in vitro receptor binding activity of a neuropeptide Y N-terminal deletion fragment

Biopolymers ◽  
1993 ◽  
Vol 33 (8) ◽  
pp. 1195-1206 ◽  
Author(s):  
Michael B. Doughty ◽  
Longqin Hu
Keyword(s):  
Neuropeptide Y ◽  
Receptor Binding ◽  
Binding Activity ◽  
Terminal Deletion ◽  
Receptor Binding Activity ◽  
Deletion Fragment

New Dimeric Tetrapeptide Enkephalin AnaloguesHydrophilic Spacer Length and Configuration Affects Potency and Receptor Selectivity

1994 ◽  
Vol 49 (3) ◽  
pp. 407-411
Author(s):  
Janusz Stępiński ◽  
S. William Tam
Keyword(s):  
Receptor Binding ◽  
Opioid Peptide ◽  
Binding Activity ◽  
High Potency ◽  
Spacer Length ◽  
Receptor Selectivity ◽  
Receptor Binding Activity ◽  
Peptide Analogues ◽  
Opioid Receptor Binding

AbstractThree new bivalent opioid peptide analogues, 1,3-di-(tyrosyl-D-alanyl-glycyl-phenylalanylamido)-2-propanol, 1,4-di-(tyrosyl-D-alanyl-glycyl-phenylalanylamido)-(2R, 3S)-butanediol and 1,4-di-(tyrosyl-D-alanyl-glycyl-phenylalanylamido)-(2R,3R)-butanediol, were synthesized and tested in vitro for μ, δ and ϰ receptor affinities. They were found to have potent opioid receptor binding activity. The (2S,3S)-butanediol bridge configuration yielded selectivity and high potency for μ and ϰ receptors, while the (2R,3R)-butanediol bridge configuration yielded high potency and selectivity for δ receptors. It thus appears that changes in the length and configuration of the polyhydroxyl bridge in dimeric enkephalin analogues can produce a shift in receptor selectivity profiles and therefore suggest the possibility of developing more selective drugs.

THE ASSAY OF HUMAN FOLLICLE-STIMULATING HORMONE PREPARATIONS: THE CHOICE OF A SUITABLE STANDARD

1979 ◽  
Vol 92 (4) ◽  
pp. 599-614 ◽  
Author(s):  
R. Marana ◽  
D. M. Robertson ◽  
H. Suginami ◽  
E. Diczfalusy
Keyword(s):  
Receptor Binding ◽  
Binding Assay ◽  
Binding Activity ◽  
Human Pituitary ◽  
Reactive Material ◽  
Receptor Binding Assay ◽  
Receptor Binding Activity ◽  
Suitable Standard ◽  
Urinary Fsh

ABSTRACT Eleven pituitary or urinary preparations of varying purity were assayed for FSH activity by an in vitro bioassay method, a receptor binding assay (RBA) technique and a radioimmunoassay (RIA) procedure, employing two anti-FSH sera with and without absorption with hCG. All methods were specific for hFSH, since other glycoproteins (hFSHα and hFSHβ subunits, hLH, hCG and hTSH) elicited little, if any, response. A partially purified hFSH preparation (1st IRP of Human Pituitary Gonadotrophins (FSH and LH/ICSH) for bioassay, code No. 69/104) was used as standard in all assays. In addition, potency estimates were expressed in terms of a highly purified hFSH preparation (hFSH-Kabi, Lot No. 19344) and in terms of the hMG (2nd IRP). Significant differences in the ratios of biological activity to receptor binding activity (B/R) and to immunological reactivity (B/I) were observed between preparations which were unrelated to their level of purity. The use of the 69/104 preparation as standard gave significantly higher B/R and B/I ratios than the use of the hMG (2nd IRP) and of a highly purified hFSH preparation. In addition, the use of the hMG (2nd IRP) as a standard gave significantly higher B/R ratios than that of the highly purified hFSH preparation. These results indicate that the 69/104 and hMG (2nd IRP) preparations contain significantly more biologically inactive receptor binding material than the more extensively purified hFSH preparation. Furthermore, the 69/104 preparation contains significantly more biologically inactive immunologically reactive material than both hMG reference standards and the highly purified hFSH preparation. It is concluded that, because of the presence in the 69/104 preparation of relatively large quantities of biologically inactive material which behaves in both the receptor binding assay (RBA) and radioimmunoassay (RIA) procedures as hFSH, this preparation is unsuitable as standard for the quantitation of FSH activity by methods other than bioassays. For the same reason, the relatively crude 2nd IRP (but not its replacement, the 1st IS for human urinary FSH and LH for bioassay) appears to be unsuitable as a standard for the assay of hFSH by RBA procedures. Among the limited number of preparations studied, a highly purified pituitary hFSH preparation appears to be the most satisfactory as a provisional standard for hFSH assays, although even this material contains some biologically inactive hFSH-like material.

Isolation and characterization of distinct bioactive forms of LH from male buffalo pituitaries: differences localized to their α subunits

1994 ◽  
Vol 143 (2) ◽  
pp. 313-323 ◽  
Author(s):  
M R Sairam ◽  
A A H Zaky ◽  
A A Hassan
Keyword(s):  
Receptor Binding ◽  
Binding Activity ◽  
Α Subunit ◽  
Basic Fraction ◽  
Isolation And Characterization ◽  
Receptor Binding Activity ◽  
Acidic Fraction ◽  
Α Subunits

Abstract The isolation of highly purified forms of pituitary LH from Egyptian male (Nile) buffaloes is described. The total LH content (receptor binding activity) which was approximately 30 to 50 fold higher than FSH in the pituitary could be divided into three pools based upon fractionation patterns on a cation exchanger. The acidic fraction which also contained FSH was not purified to homogeneity. A basic fraction (bu-LH-2; 300 mg/kg anterior pituitary) and a very basic fraction (bu-LH-3; 80 mg/kg) were both highly purified and free of FSH activity as tested by specific FSH receptor and immunoassays. The basic buffalo LH fraction, bu-LH-2, was as active as highly purified ovine LH (oLH). The most basic form of buffalo LH, bu-LH-3, was, however, about twice as active as highly purified oLH in the in vitro bioassay using mouse Leydig tumour (MA-10) cells. In a receptor binding assay employing 125I-labelled buffalo LH (bu-LH-3) and porcine testicular membranes, the affinity of bu-LH-3 was about five times higher than purified oLH. The Mr of both forms of purified buffalo LH and subunits was similar to that of oLH. Amino acid composition of buffalo LH was also very similar to oLH except for small differences. Fractionation by fast protein liquid chromatography on Mono-Q columns revealed further evidence of microheterogeneity in each of the pools of buffalo LH with bu-LH-3 exhibiting a predominant single component. By reverse-phase high-pressure liquid chromotography analysis we have localized differences in the two purified isoforms of male buffalo LH to the α subunit. It is suggested that differences in biological potencies could be due to variations in terminal glycosylation and/or differences in branching of this subunit which is known to be important for signal transduction. Journal of Endocrinology (1994) 143, 313–323

scholarly journals Chemical deglycosylation of ovine pituitary lutropin. A study of the reaction conditions and effects on biochemical, biophysical and biological properties of the hormone

1982 ◽  
Vol 207 (1) ◽  
pp. 11-19 ◽  
Author(s):  
P. Manjunath ◽  
M. R. Sairam ◽  
P. W. Schiller
Keyword(s):  
Receptor Binding ◽  
Conformational Changes ◽  
Concanavalin A ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Binding Activity ◽  
Glycoprotein Hormone ◽  
Reaction Conditions ◽  
Receptor Binding Activity

The oligomeric glycoprotein hormone, ovine lutropin was treated with anhydrous HF at 0°C for 30, 60 and 180 min and at 23°C for 60 and 180 min. The products, designated deglycosylated lutropin 1 (DGLH-1) to deglycosylated lutropin 5 (DGLH-5) respectively, were characterized by gel filtration, concanavalin A–Sepharose binding, disc electrophoresis, amino acid analysis, carbohydrate composition and spectral properties. The preparations were also evaluated for receptor binding activity and immunological activity and bioassayed in vitro in collagenase-dispersed rat interstitial cells. In DGLH-1, fucose and galactosamine were removed completely, and there was a 94% decrease in hexoses and 39% decrease in N-acetylglucosamine. Reaction with HF at 0°C for 1 or 3h led to removal of all hexoses and additional loss of hexosamines. Reactions at 23°C for either 1 or 3h were not of additional value in deglycosylation and none of the reaction conditions yielded the apohormone. All the five deglycosylated hormone preparations were not retained on immobilized-concanavalin A columns and on Sephadex G-100 they were eluted with an increased Ve/V0 ratio consistent with the loss of carbohydrate residues. Loss of all but the last of the N-acetylglucosamine residues decreased the abnormality of lutropin on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, but did not eliminate it. Receptor binding activities of DGLH-1 and DGLH-2 were not different from that of the native hormone, but that of DGLH-3 was slightly decreased and the products obtained at 23°C (DGLH-4 and DGLH-5) had lower activity. Immunoreactivities followed a similar pattern. None of the derivatives had activity in the bioassay in vitro. All of the five derivatives inhibited the action of the native hormone in the bioassay in vitro. Their hormonal antagonistic activity was consistent with the receptor binding activity, with DGLH-5 being the least potent in this respect. The DGLH-4 and DGLH-5 preparations had undergone conformational changes as revealed by 8-anilinonaphthalene-1-sulphonate fluorescence, but this did not result in loss of quaternary structure.

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