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A Comparison of sex steroid binding protein (SBP) in four species of teleost fish


Hobby, AC and Pankhurst, NW and Geraghty, DP, A Comparison of sex steroid binding protein (SBP) in four species of teleost fish, Fish Physiology and Biochemistry, 23, (3) pp. 245-256. ISSN 0920-1742 (2000) [Refereed Article]

DOI: doi:10.1023/A:1007869713348


A sex steroid binding protein (SBP) binding E2 with high affinity has been detected in a pleuronectid (greenback flounder Rhombosolea tapirina), two sparids (black bream Acanthopagrus butceri and snapper Pagrus auratus), and its presence has been confirmed in a salmonid (rainbow trout Oncorhynchus mykiss). SBP binding characteristics were measured using a hot saturation assay for trout, bream and snapper, and a cold saturation assay for flounder. Bound and unbound steroid were separated by incubation with dextran-coated charcoal (DCC). Affinity for E2 was highest in trout (kD = 0.44 nM), followed by bream (kD = 3.39 nM) and snapper (kD = 10.7 nM). The lowest affinity was found in flounder (kD = 84.7 nM). Binding capacity, however, was greatest in flounder (Bmax = 164 nM), followed by trout (Bmax = 92 nM), and then bream and snapper (Bmax = 50 and 39 nM, respectively). Binding of E2 to SBP had a very rapid rate of association, and most dissociation occurred within 5 min. To confirm that the plasma protein measured here was SBP, the relative binding affinities of SBP for a range of steroids were measured. In trout, bream and snapper, SBP bound E2 with the highest affinity, followed by T. In contrast, the relative affinity of T for flounder SBP was more than twice that of E2. The rank orders of affinity of binding indicate the importance of an unhindered 17β-hydroxyl group, and a 3-hydroxyl or 3-ketone group for high affinity binding to SBP. These requirements for high affinity binding are present in most animals possessing SBP and indicate conservation of the SBP molecule through evolution.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Aquaculture
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - aquaculture
Objective Field:Fisheries - aquaculture not elsewhere classified
UTAS Author:Hobby, AC (Mrs Andrea Cherie Hobby)
UTAS Author:Pankhurst, NW (Professor Ned Pankhurst)
UTAS Author:Geraghty, DP (Professor Dominic Geraghty)
ID Code:22025
Year Published:2000
Web of Science® Times Cited:13
Deposited By:TAFI - Aquaculture
Deposited On:2001-08-01
Last Modified:2011-10-04

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