Partial purification and characterization of a membrane-associated steroid-binding protein from Pseudomonas testosteroni

1982 ◽  
Vol 60 (8) ◽  
pp. 798-803 ◽  
Author(s):  
Mike Francis ◽  
Mamoru Watanabe
Keyword(s):  
Binding Protein ◽  
Membrane Vesicles ◽  
Activity Analysis ◽  
Binding Activity ◽  
Regulatory Function ◽  
Partial Purification ◽  
Purification And Characterization ◽  
Steroid Binding ◽  
Steroid Binding Protein

A steroid-binding protein obtained from the supernatant of the final wash from the preparation of membrane vesicles was purified severalfold to near homogeneity. The protein binds C18 and C19 steroids but has the highest affinity for androstenedione (Kd = 1.6 × 10−10 M). The molecular weight is 51 000 – 58 000. Binding activity is slightly inhibited by Cu2+, Ca2+, and Mg2+ and completely inhibited by Zn2+. The protein has no detectable steroid degradative activity. Analysis of androstenedione binding revealed negative cooperativity of binding for this ligand and may indicate a regulatory function for this protein. It is postulated that this protein binds the steroid after testosterone is converted to androstenedione.

Purification and characterization of the sex steroid-binding protein from macaque serum. Comparison with the human protein

Biochemistry ◽  
1984 ◽  
Vol 23 (3) ◽  
pp. 492-497 ◽  
Author(s):  
Eric E. Turner ◽  
J. B. Alexander Ross ◽  
Pearl C. Namkung ◽  
Philip H. Petra
Keyword(s):  
Binding Protein ◽  
Human Protein ◽  
Sex Steroid ◽  
Purification And Characterization ◽  
Steroid Binding ◽  
Steroid Binding Protein

Purification and characterization of a membrane-associated testosterone-binding protein from Pseudomonas testosteroni

1983 ◽  
Vol 61 (5) ◽  
pp. 307-312 ◽  
Author(s):  
Mike McD. Francis ◽  
Mamoru Watanabe
Keyword(s):  
Binding Protein ◽  
Divalent Cations ◽  
Membrane Surface ◽  
Membrane Vesicles ◽  
Affinity Constant ◽  
Steroid Binding Proteins ◽  
Steroid Binding ◽  
Steroid Binding Protein ◽  
Pseudomonas Testosteroni

A steroid-binding protein, identified in the supernatant generated when membrane vesicles of Pseudomonas testosteroni are produced and harvested by centrifugation, has been purified 49-fold to homogeneity. It has a molecular weight of 30 000 – 35 000 and it specifically binds the C19 steroids dihydrotestosterone, testosterone, and androstenedione. It is a basic protein with an isoelectric point at pH 7.3. Binding of testosterone exhibited normal saturation kinetics with an affinity constant, Kd, of 3.9 × 10−8 M. Binding was inhibited by divalent cations, but the sulfhydryl reagents dithiothreitol and mercaptoethanol did not affect activity. It is suggested that this and other membrane-associated steroid-binding proteins concentrate the steroid at the membrane surface before it is transported into the cytoplasm of P. testosteroni.

Foetal steroid binding protein in British and Japanese women

1987 ◽  
Vol 114 (4) ◽  
pp. 584-588 ◽  
Author(s):  
M. Jawed Iqbal ◽  
Alastair Forbes ◽  
Mark L. Wilkinson ◽  
John W. Moore ◽  
Roger Williams ◽  
...  
Keyword(s):  
Ovarian Function ◽  
Binding Protein ◽  
Premenopausal Women ◽  
Japanese Women ◽  
Sex Hormone Binding Globulin ◽  
Partial Purification ◽  
Enzyme Linked Immunosorbent Assay ◽  
Binding Characteristics ◽  
Steroid Binding ◽  
Steroid Binding Protein

Abstract. In order to examine the newly-discovered sex-steroid binding protein, foetal steroid binding protein (FSBP) in different populations, its binding characteristics and its level were studied by two-tier column ligand binding assay and enzyme-linked immunosorbent assay (ELISA) respectively. In 10 Japanese premenopausal women, analysis of 5α-dihydrotestosterone (DHT) binding in the Cibacron Blue 3GA-Sepharose 6B portion of the column showed a rising plateau pattern with a mean maximum binding of 31.1 ± 7.41%, whereas of 9 similar British women, 8 displayed unsaturable, non-cooperative binding of 11.6 ± 8.22% (P < 0.01). After partial purification of FSBP in these samples, the protein exhibited saturable binding kinetics, median binding 25 (interquartiles 23–34) and 19 (13–25) nmol DHT/l in Japanese and British women, respectively (P < 0.05). By analyzing FSBP by ELISA in 56 Japanese (45 premenopausal) and 59 British (25 premenopausal) women, higher levels were obtained in the whole Japanese group (P = 0.0016) and in the premenopausal Japanese women (P = 0.018) than in their British counterparts. In both nationalities, FSBP levels were higher in premenopausal women, and there was a significant negative correlation of FSBP with age in both populations, particularly in postmenopausal women. FSBP levels did not correlate with weight, parity, sex hormone binding globulin or albumin levels. The influence of FSBP on free steroid levels remains unclear, but some relationship with ovarian function seems a possibility.

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